/*
 * 音樂 Music（/resources/classes/music/）專屬樣式。
 * 共用的版面在 astro.css（.astro-lab、.al-*、.ph-card、.cc-card、.myth、.trick、.act）；這裡的 class 前綴一律 mu-。
 * 只載在本系列的頁面（build.py 的 _mus_head()）。中文一律系統字（var(--zh)），不載中文網頁字型。
 */

/* ── 開啟聲音列（整頁共用，捲動時黏在上方） ─────────────────────────── */
.mu-soundwrap { position: sticky; top: 76px; z-index: 80; background: rgba(10,16,34,.94); backdrop-filter: blur(8px); border-bottom: 1px solid rgba(160,180,230,.25); }
.mu-soundbar { display: flex; flex-wrap: wrap; align-items: center; gap: .55rem 1.2rem; padding: .6rem 0; color: #e8edf7; }
.mu-sound-btn { display: inline-flex; align-items: center; gap: .55rem; padding: .6rem 1.15rem; border-radius: 999px; border: 2px solid #ffd36e; background: #ffd36e; color: #1b1405; font-family: var(--sans); font-weight: 800; font-size: .95rem; cursor: pointer; transition: background .2s, transform .2s; }
.mu-sound-btn:hover:not(:disabled) { transform: translateY(-1px); background: #ffe08f; }
.mu-sound-btn:focus-visible { outline: 3px solid #fff; outline-offset: 2px; }
.mu-sound-btn:disabled { opacity: .6; cursor: default; }
.mu-sound-btn .zh { font-family: var(--zh); font-weight: 700; margin-left: .15rem; }
.mu-sound-ic { font-size: 1.25rem; line-height: 1; }
.mu-soundbar[data-state="on"] .mu-sound-btn { background: transparent; color: #ffd36e; }
.mu-soundbar[data-state="muted"] .mu-sound-btn { background: transparent; color: #ffb4a2; border-color: #ffb4a2; }
.mu-vol { display: inline-flex; align-items: center; gap: .6rem; font-size: .82rem; font-weight: 700; color: #cfd8ee; }
.mu-vol b { margin-left: .25rem; color: #fff; font-variant-numeric: tabular-nums; }
.mu-vol input { width: 150px; accent-color: #ffd36e; }
.mu-sound-note { flex: 1 1 260px; margin: 0; font-size: .78rem; line-height: 1.5; color: #9fb0cf; }
.mu-sound-note .zh { display: block; }
.mu-sound-note[hidden] { display: none; }
@media (max-width: 620px) {
  .mu-soundbar { flex-wrap: nowrap; gap: .5rem .7rem; padding: .4rem 0; }
  .mu-sound-btn { padding: .45rem .8rem; font-size: .82rem; flex: none; }
  .mu-vol { flex: 1; min-width: 0; gap: .4rem; font-size: .74rem; }
  .mu-vol > span { white-space: nowrap; }
  .mu-vol input { width: 100%; min-width: 60px; }
  .mu-sound-note { display: none; }
}

/* ── 3D 模型：單弦琴 ─────────────────────────────────────────────────── */
.mu-lab .al-stage { grid-template-columns: minmax(0, 1fr) 360px; }
.mu-lab .al-space { min-height: 520px; background: radial-gradient(70% 60% at 50% 40%, rgba(255,201,74,.10), transparent 70%); }
.mu-lab .al-space-cv { touch-action: pan-y; }
.mu-lab .al-hint { left: auto; right: 1rem; text-align: right; }
.al-lab.mu-lb { font-size: .76rem; font-weight: 800; line-height: 1.25; padding: .08rem .45rem; color: var(--al-mute); white-space: nowrap; font-variant-numeric: tabular-nums; }
.al-lab.mu-lb-live { color: #1b1405; background: rgba(255,211,110,.95); border-color: #ffd36e; }
.al-lab.mu-lb-dead { color: #cfd8ee; }
.al-lab.mu-lb-tick { color: #ffe3a3; border-color: rgba(201,161,74,.6); min-width: 1.6em; text-align: center; }
.al-lab.mu-lb[hidden] { display: none; }
.mu-narrow .al-lab.mu-lb { font-size: .66rem; padding: .04rem .3rem; }

.mu-aside { display: flex; flex-direction: column; gap: .55rem; }
.mu-aside > * { min-width: 0; }
.mu-aside .al-sky-k { margin-bottom: 0; }
.mu-freq { margin: 0; font-family: var(--serif); font-size: 3.4rem; font-weight: 700; line-height: 1; color: #fff; font-variant-numeric: tabular-nums; }
.mu-freq small { font-size: 1.2rem; font-weight: 700; color: var(--al-mute); font-family: var(--sans); }
.mu-note { margin: 0; font-size: 1.5rem; font-weight: 800; color: var(--al-sun); }
.mu-note span { font-size: 1rem; color: var(--al-mute); font-weight: 700; }
.mu-cents { margin: 0; min-height: 2.6em; font-size: .8rem; line-height: 1.5; color: var(--al-mute); }
.mu-cents .zh { display: block; }
.mu-facts { margin: .2rem 0 0; padding-top: .55rem; border-top: 1px solid var(--al-line); display: grid; gap: .35rem; }
.mu-facts div { display: flex; justify-content: space-between; align-items: baseline; gap: .8rem; }
.mu-facts dt { font-size: .7rem; font-weight: 700; letter-spacing: .03em; color: var(--al-mute); }
.mu-facts dd { margin: 0; font-size: 1.02rem; font-weight: 800; color: #fff; font-variant-numeric: tabular-nums; text-align: right; }
.mu-facts dd small { font-size: .7rem; color: var(--al-mute); font-weight: 700; display: block; }
.mu-slide { display: block; font-size: .72rem; font-weight: 700; letter-spacing: .05em; text-transform: uppercase; color: var(--al-mute); }
.mu-slide input { display: block; width: 100%; margin-top: .35rem; accent-color: #ffd36e; }
.mu-presets { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .3rem; }
.mu-presets button { padding: .42rem .2rem; border-radius: 11px; border: 1px solid var(--al-line); background: rgba(255,255,255,.03); color: var(--al-text); font-family: var(--sans); font-size: .76rem; line-height: 1.25; cursor: pointer; }
.mu-presets button b { display: block; font-weight: 800; }
.mu-presets button small { display: block; font-family: var(--zh); font-weight: 600; color: var(--al-mute); }
.mu-presets button[aria-pressed="true"] { border-color: var(--al-sun); background: rgba(255,211,110,.14); box-shadow: 0 0 0 1px var(--al-sun) inset; }
.mu-btn { display: inline-flex; align-items: center; justify-content: center; gap: .4rem; padding: .55rem 1.1rem; border-radius: 999px; border: 1px solid var(--line); background: #fff; color: var(--brand-dk); font-family: var(--sans); font-weight: 800; font-size: .86rem; line-height: 1.3; cursor: pointer; transition: background .2s, border-color .2s, transform .2s; }
.mu-btn:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-1px); }
.mu-btn:disabled { opacity: .45; cursor: default; }
.mu-btn-gold { background: var(--gold); border-color: var(--gold); color: #1b1405; }
.mu-btn-gold:hover:not(:disabled) { background: var(--gold-dk); color: #fff; }
.mu-btn[hidden] { display: none; }
.mu-aside .mu-btn { background: rgba(255,211,110,.14); border-color: rgba(255,211,110,.5); color: var(--al-sun); }
.mu-aside .mu-btn-gold { background: var(--al-sun); border-color: var(--al-sun); color: #1b1405; }
.mu-msg { margin: 0; min-height: 6em; font-size: .82rem; line-height: 1.6; color: var(--al-text); }
.mu-msg .zh { display: block; margin-top: .25rem; color: var(--al-mute); }
.mu-slowline { margin: 0; padding-top: .5rem; border-top: 1px solid var(--al-line); font-size: .74rem; line-height: 1.55; color: var(--al-mute); }
.mu-slowline b { color: #fff; }
.mu-slowline .zh { display: block; }
.mu-credit { margin: 0; padding: 0 1.3rem 1.1rem; font-size: .74rem; line-height: 1.6; color: #7f90b0; }
.al-lg-live i { border-color: #ffd36e; background: rgba(255,211,110,.35); }
.al-lg-dead i { border-color: #7d8aa6; background: rgba(125,138,166,.3); }
.al-lg-tick i { border-color: #ffe3a3; border-radius: 3px; width: 6px; margin-left: 6px; margin-right: 6px; }
.mu-lab.al-nogl .al-sky { display: flex; }
.mu-lab.al-nogl .al-controls { display: block; }
.mu-lab.al-nogl .al-space { min-height: 150px; aspect-ratio: auto; border-right: 0; border-bottom: 1px solid var(--al-line); }
@media (max-width: 1000px) {
  .mu-lab .al-stage { grid-template-columns: minmax(0, 1fr); }
  .mu-lab .al-space { aspect-ratio: 16 / 9; min-height: 320px; max-height: 80vh; border-right: 0; border-bottom: 1px solid var(--al-line); }
  .mu-msg { min-height: 4.6em; }
}
@media (max-width: 620px) {
  .mu-lab .al-space { aspect-ratio: 16 / 11; min-height: 0; max-height: 70vh; }
  .mu-lab .al-hint { display: none; }
  .mu-freq { font-size: 2.8rem; }
  .mu-msg { min-height: 7.4em; }
}

/* ── 卡片與課程卡小圖 ─────────────────────────────────────────────────── */
.mu-ico { background: radial-gradient(circle at 50% 40%, #fff8e3, #f1dfae); font-size: 2.2rem; }
.mu-lc-ico { background: radial-gradient(circle at 50% 38%, #1b2f5c, #070b17); }

/* ── 哪一個比較高？ ──────────────────────────────────────────────────── */
.mu-higher { margin-top: 1.5rem; padding: 1.5rem 1.6rem 1.4rem; background: #0c1428; color: #e8edf7; border-radius: 20px; box-shadow: var(--shadow); max-width: 860px; }
.mu-hg-top { display: flex; flex-wrap: wrap; justify-content: space-between; gap: .4rem 1rem; align-items: baseline; }
.mu-hg-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: #ffd36e; }
.mu-hg-sc { margin: 0; font-size: .82rem; color: #9fb0cf; }
.mu-hg-score { margin-left: .3rem; font-size: 1.05rem; color: #fff; font-variant-numeric: tabular-nums; }
.mu-hg-steps { display: flex; gap: .35rem; margin: .9rem 0 0; }
.mu-hg-steps i { flex: 1; height: 6px; border-radius: 3px; background: #2b3550; }
.mu-hg-steps i.is-past { background: #4a7bd6; }
.mu-hg-steps i.is-now { background: #ffd36e; }
.mu-hg-stage { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .8rem; margin-top: 1.1rem; }
.mu-hg-opt { display: flex; flex-direction: column; align-items: center; gap: .35rem; padding: 1rem .6rem; border-radius: 16px; border: 1px solid rgba(160,180,230,.3); background: rgba(255,255,255,.05); color: #fff; font-family: var(--sans); cursor: pointer; transition: background .15s, border-color .15s, transform .15s; }
.mu-hg-opt:hover:not(:disabled) { background: rgba(255,255,255,.12); transform: translateY(-2px); }
.mu-hg-opt:disabled { cursor: default; opacity: .55; }
.mu-hg-n { display: grid; place-items: center; width: 2.2rem; height: 2.2rem; border-radius: 50%; background: #ffd36e; color: #1b1405; font-weight: 800; font-size: 1.1rem; }
.mu-hg-lab { font-weight: 800; font-size: .92rem; text-align: center; line-height: 1.35; }
.mu-hg-lab .zh { display: block; font-weight: 600; color: #9fb0cf; }
.mu-hg-hz { min-height: 1.3em; font-size: .9rem; font-weight: 700; color: #ffe3a3; font-variant-numeric: tabular-nums; }
.mu-hg-opt.is-right { background: #2f9e63; border-color: #7ee0aa; opacity: 1; }
.mu-hg-opt.is-wrong { background: rgba(214,69,69,.35); border-color: #e08a8a; text-decoration: line-through; }
.mu-hg-playing .mu-hg-play { box-shadow: 0 0 0 4px rgba(255,211,110,.35); }
.mu-hg-playrow { display: flex; justify-content: center; margin-top: 1rem; }
.mu-hg-nosound { margin: .9rem 0 0; padding: .6rem .9rem; border-radius: 10px; background: rgba(255,179,162,.12); font-size: .84rem; color: #ffd6cb; }
.mu-hg-nosound[hidden] { display: none; }
.mu-hg-nosound .zh { display: block; }
.mu-hg-msg { margin: 1rem 0 .9rem; min-height: 3.6em; font-size: .95rem; line-height: 1.6; }
.mu-hg-msg .zh { display: block; color: #9fb0cf; }
.mu-hg-foot { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: .7rem 1rem; }
.mu-check { display: inline-flex; align-items: center; gap: .5rem; font-size: .84rem; color: #9fb0cf; cursor: pointer; }
.mu-check input { width: 18px; height: 18px; accent-color: #ffd36e; }

/* ── 可以彈的鍵盤 ────────────────────────────────────────────────────── */
.mu-keys { margin-top: 1.5rem; padding: 1.4rem 1.5rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 900px; }
.mu-k-top { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: .6rem 1rem; }
.mu-k-octave { margin: 0; font-size: .86rem; font-weight: 700; color: var(--ink-soft); }
.mu-k-oct { margin-left: .4rem; font-size: 1.05rem; color: var(--brand-dk); }
.mu-k-btns { display: flex; flex-wrap: wrap; gap: .45rem; }
.mu-kb { position: relative; height: 210px; margin-top: 1rem; border-radius: 0 0 10px 10px; background: #1b1405; padding: 0; touch-action: none; user-select: none; -webkit-user-select: none; }
.mu-key { position: absolute; top: 0; margin: 0; padding: 0; border: 0; cursor: pointer; font-family: var(--sans); touch-action: none; -webkit-tap-highlight-color: transparent; }
.mu-white { height: 100%; background: linear-gradient(#fdfaf2, #fff 70%, #e9e3d2); border: 1px solid #8e8570; border-top: 0; border-radius: 0 0 8px 8px; z-index: 1; display: flex; align-items: flex-end; justify-content: center; box-sizing: border-box; }
.mu-black { height: 62%; background: linear-gradient(#1c1c1c, #000); border-radius: 0 0 6px 6px; z-index: 2; box-shadow: 0 3px 5px rgba(0,0,0,.5); }
.mu-key-n { padding-bottom: .55rem; font-size: .8rem; font-weight: 800; color: #4a4636; line-height: 1.2; text-align: center; pointer-events: none; }
.mu-key-n small { display: block; font-size: .68rem; color: #8a8267; font-weight: 700; }
.mu-white.is-down { background: linear-gradient(#ffe9a8, #ffd36e); }
.mu-black.is-down { background: linear-gradient(#5a4a1a, #2a2208); }
.mu-key.is-last { outline: 3px solid var(--brand); outline-offset: -3px; }
.mu-key:focus-visible { outline: 3px solid var(--brand); outline-offset: -3px; z-index: 3; }
.mu-k-read { display: grid; grid-template-columns: minmax(0, .9fr) minmax(0, 1.4fr); gap: 1rem 1.4rem; margin-top: 1.1rem; align-items: stretch; }
.mu-k-now { padding: .9rem 1.1rem; border-radius: 14px; background: var(--cream); border: 1px solid var(--line); }
.mu-k-kk { margin: 0; font-size: .72rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; color: var(--gold-dk); }
.mu-k-name { margin: .2rem 0 0; font-size: 1.5rem; font-weight: 800; color: var(--brand-dk); }
.mu-k-name span { font-size: 1rem; color: var(--ink-soft); font-weight: 700; }
.mu-k-hz { margin: .1rem 0 0; font-family: var(--serif); font-size: 1.8rem; font-weight: 700; font-variant-numeric: tabular-nums; }
.mu-k-hz small, .mu-k-cell small { font-family: var(--sans); font-size: .8rem; color: var(--ink-soft); font-weight: 700; }
.mu-k-tab { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: .5rem; }
.mu-k-cell { display: flex; flex-direction: column; justify-content: center; gap: .15rem; padding: .7rem .6rem; border-radius: 14px; border: 1px solid var(--line); background: #fff; text-align: center; }
.mu-k-cell span { font-size: .7rem; font-weight: 700; color: var(--ink-soft); line-height: 1.3; }
.mu-k-cell b { font-size: 1.15rem; font-variant-numeric: tabular-nums; }
.mu-k-cell i { font-style: normal; font-size: .82rem; font-weight: 800; color: var(--gold-dk); min-height: 1.1em; }
.mu-k-mid { background: #fff8e6; border-color: var(--gold); }
.mu-k-msg { margin: .9rem 0 0; min-height: 3.2em; font-size: .92rem; line-height: 1.6; }
.mu-k-msg span { display: block; font-weight: 700; font-variant-numeric: tabular-nums; }
.mu-k-msg .zh { color: var(--ink-soft); font-weight: 500; }
.mu-k-tip { margin: .2rem 0 0; font-size: .78rem; color: var(--ink-soft); }

/* ── 人耳聽得到的範圍 ────────────────────────────────────────────────── */
.mu-range { margin-top: 1.5rem; padding: 1.5rem 1.6rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 900px; }
.mu-rg-top { display: flex; flex-wrap: wrap; align-items: baseline; gap: .3rem 1.4rem; }
.mu-rg-hz { margin: 0; font-family: var(--serif); font-size: 3rem; font-weight: 700; line-height: 1; color: var(--brand-dk); font-variant-numeric: tabular-nums; }
.mu-rg-hz small { font-family: var(--sans); font-size: 1.1rem; color: var(--ink-soft); font-weight: 700; }
.mu-rg-note { margin: 0; font-size: .95rem; font-weight: 700; }
.mu-rg-note .zh { display: block; color: var(--ink-soft); font-weight: 500; }
.mu-rg-scale { margin-top: 1.4rem; }
.mu-rg-marks { position: relative; height: 1.6rem; margin: 0 12px; }
.mu-rg-m { position: absolute; top: 0; transform: translateX(-50%); font-size: .72rem; font-weight: 700; color: var(--ink-soft); font-variant-numeric: tabular-nums; }
.mu-rg-piano { position: absolute; left: 0; bottom: -2px; height: 7px; border-radius: 4px; background: var(--gold); opacity: .85; }
.mu-rg-slider { display: block; width: 100%; accent-color: var(--brand); }
.mu-rg-keyline { margin: .5rem 0 0; font-size: .78rem; color: var(--ink-soft); }
.mu-rg-keyline i { display: inline-block; width: 22px; height: 7px; border-radius: 4px; background: var(--gold); vertical-align: middle; margin-right: .3rem; }
.mu-rg-btns { display: flex; flex-wrap: wrap; gap: .4rem; margin-top: 1rem; }
.mu-rg-btns .mu-btn { padding: .35rem .8rem; font-size: .8rem; }
.mu-rg-play { margin-top: 1.1rem; }
.mu-rg-hold { touch-action: none; user-select: none; -webkit-user-select: none; }
.is-playing .mu-rg-hold { background: var(--brand); border-color: var(--brand); color: #fff; }
.mu-rg-msg { margin: .8rem 0 0; font-size: .86rem; line-height: 1.6; color: var(--ink-soft); }
.mu-rg-msg .zh { display: block; }

/* ── 課綱、安全、延伸、出處 ──────────────────────────────────────────── */
.mu-curric { list-style: none; margin: 1.4rem 0 0; padding: 0; display: grid; gap: .9rem; max-width: 900px; }
.mu-cur { padding: 1.1rem 1.3rem; background: #fff; border: 1px solid var(--line); border-left: 5px solid var(--gold); border-radius: 14px; box-shadow: var(--shadow-sm); }
.mu-cur-k { margin: 0; display: flex; flex-wrap: wrap; gap: .2rem .8rem; align-items: baseline; font-size: .82rem; color: var(--ink-soft); }
.mu-cur-k b { font-size: 1rem; color: var(--brand-dk); font-variant-numeric: tabular-nums; }
.mu-cur-q { margin: .4rem 0 0; font-size: 1rem; line-height: 1.7; font-family: var(--zh); }
.mu-cur-n { margin: .5rem 0 0; font-size: .88rem; line-height: 1.6; color: var(--ink-soft); }
.mu-cur-n .zh { display: block; }
.mu-safety { list-style: none; margin: 1.4rem 0 0; padding: 0; display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .9rem 1.1rem; }
.mu-safety li { position: relative; padding: 1rem 1.2rem 1rem 3.1rem; background: #fff; border: 1px solid #f0c9b8; border-radius: 14px; font-size: .98rem; line-height: 1.65; box-shadow: var(--shadow-sm); }
.mu-safety li::before { content: "\26A0"; position: absolute; left: 1.05rem; top: .95rem; font-size: 1.2rem; color: var(--sunset); }
.mu-safety li .zh { display: block; margin-top: .3rem; color: var(--ink-soft); font-size: .93rem; }
.mu-links { display: grid; gap: 1rem; margin-top: 1.4rem; max-width: 860px; }
.mu-link { display: flex; gap: 1.1rem; align-items: flex-start; padding: 1.2rem 1.4rem; border-radius: 18px; background: #fff; border: 1px solid var(--line); box-shadow: var(--shadow-sm); color: var(--ink); transition: transform .25s, box-shadow .25s, border-color .25s; }
a.mu-link:hover { transform: translateY(-3px); box-shadow: var(--shadow); border-color: var(--gold); color: var(--ink); }
.mu-link-soon { border-style: dashed; background: linear-gradient(120deg, #fff, var(--cream)); }
.mu-link-ic { flex: none; display: grid; place-items: center; width: 64px; height: 64px; border-radius: 18px; background: radial-gradient(circle at 50% 38%, #1b2f5c, #070b17); font-size: 2rem; }
.mu-link-b { display: flex; flex-direction: column; gap: .15rem; min-width: 0; }
.mu-link-k { font-size: .74rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; color: var(--gold-dk); }
.mu-link-b b { font-family: var(--serif); font-size: 1.2rem; line-height: 1.3; }
.mu-link-zh { font-size: 1rem; font-weight: 600; color: var(--ink-soft); }
.mu-link-n { margin-top: .4rem; font-size: .92rem; line-height: 1.6; }
.mu-link-n .zh { display: block; margin-top: .2rem; color: var(--ink-soft); }
.mu-link-go { align-self: flex-start; margin-top: .6rem; font-weight: 800; font-size: .82rem; color: var(--brand-dk); background: var(--brand-lt); border-radius: 999px; padding: .38rem .85rem; }
.mu-link-soon .mu-link-go { color: var(--ink-soft); background: var(--cream); border: 1px solid var(--line); }
.mu-sources { margin: 0 0 2.4rem; padding: 1.3rem 1.5rem; border: 1px solid var(--line); border-radius: 16px; background: var(--cream); }
.mu-sources .sub-head { margin-top: 0; }
.mu-sources > .muted { margin: .2rem 0 .8rem; font-size: .9rem; }
.mu-sources ol { margin: 0; padding-left: 1.3em; display: grid; gap: .55rem; }
.mu-sources li { font-size: .92rem; line-height: 1.55; }
.mu-sources li > span { display: block; }
.mu-sources li .zh { display: inline; margin-left: .4rem; color: var(--ink-soft); font-size: .88rem; }
.mu-sources a { font-weight: 700; font-size: .86rem; color: var(--brand-dk); overflow-wrap: anywhere; }
.mu-progress { font-weight: 700; color: var(--brand-dk); }
.mu-intro-ic { float: right; margin: 0 0 .8rem 1.2rem; display: grid; place-items: center; width: 104px; height: 104px; border-radius: 26px; background: radial-gradient(circle at 50% 38%, #1b2f5c, #070b17); box-shadow: 0 14px 30px -18px rgba(6,12,30,.9); }

@media (max-width: 860px) { .mu-k-read { grid-template-columns: 1fr; } }
@media (max-width: 760px) { .mu-safety { grid-template-columns: 1fr; } }
@media (max-width: 560px) {
  .mu-link { flex-direction: column; }
  .mu-intro-ic { width: 80px; height: 80px; } .mu-intro-ic svg { width: 58px; height: 58px; }
  .mu-higher, .mu-keys, .mu-range { padding: 1.1rem; }
  .mu-hg-stage { grid-template-columns: 1fr; }
  .mu-kb { height: 170px; }
  .mu-key-n { font-size: .66rem; padding-bottom: .35rem; } .mu-key-n small { font-size: .56rem; }
  .mu-k-cell b { font-size: 1rem; }
  .mu-rg-hz { font-size: 2.4rem; }
}

/* ── 第二課：弦的諧波（3D 與右邊欄） ─────────────────────────────────── */
.al-lab.mu-lb-mode { font-size: .72rem; color: #e8edf7; background: rgba(12,20,40,.82); }
.al-lab.mu-lb-mode.is-zero { color: #ffb4a2; text-decoration: line-through; }
.mu-freq-sm { font-size: 1.9rem; }
.mu-freq-sm b { color: var(--al-sun); }
.mu-freq-sm small { font-size: .85rem; }
.mu-k2 { margin-top: .2rem !important; }
.mu-bars { display: grid; grid-template-columns: repeat(8, minmax(0, 1fr)); gap: .25rem; align-items: end; height: 120px; }
.mu-bar { position: relative; display: flex; flex-direction: column; justify-content: flex-end; align-items: center; height: 100%; }
.mu-bar-v { display: block; width: 100%; height: calc(var(--v, 0) * 74px + 3px); min-height: 3px; border-radius: 4px 4px 0 0; background: var(--c); transition: height .2s; }
.mu-bar.is-off .mu-bar-v { opacity: .22; }
.mu-bar.is-zero .mu-bar-v { background: transparent; border: 1px dashed #ffb4a2; border-bottom: 0; }
.mu-bar-n { font-size: .78rem; font-weight: 800; color: #fff; }
.mu-bar-f { font-size: .56rem; color: var(--al-mute); white-space: nowrap; font-variant-numeric: tabular-nums; }
.mu-bar > .mu-bar-n { order: 3; margin-top: .15rem; }
.mu-bar > .mu-bar-f { order: 4; }
.mu-bar > .mu-bar-v { order: 2; }
.mu-modes { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: .3rem; }
.mu-modes button { padding: .42rem 0; border-radius: 10px; border: 1px solid var(--al-line); background: rgba(255,255,255,.03); color: var(--al-mute); font-family: var(--sans); font-weight: 800; font-size: .9rem; cursor: pointer; }
.mu-modes button[aria-pressed="true"] { background: var(--al-sun); border-color: var(--al-sun); color: #1b1405; }
.mu-presets-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }

/* ── 混合諧波 ────────────────────────────────────────────────────────── */
.mu-mix, .mu-env, .mu-which { margin-top: 1.5rem; padding: 1.5rem 1.6rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 940px; }
.mu-mx-grid, .mu-ev-grid { display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr); gap: 1.4rem 2rem; align-items: start; }
.mu-mx-sliders { display: grid; gap: .45rem; }
.mu-mx-row { display: grid; grid-template-columns: 1.6rem minmax(0, 1fr) 4.6rem 2.8rem; align-items: center; gap: .5rem; font-size: .8rem; }
.mu-mx-n { display: grid; place-items: center; width: 1.5rem; height: 1.5rem; border-radius: 50%; background: var(--c); color: #1b1405; font-weight: 800; font-size: .8rem; }
.mu-mx-row input { width: 100%; accent-color: var(--c); }
.mu-mx-f { color: var(--ink-soft); font-variant-numeric: tabular-nums; text-align: right; }
.mu-mx-row output { font-weight: 800; font-variant-numeric: tabular-nums; text-align: right; }
.mu-mx-cv, .mu-ev-cv { display: block; width: 100%; height: 150px; border: 1px solid var(--line); border-radius: 12px; background: #fff; }
.mu-mx-cap { margin: .35rem 0 .8rem; font-size: .76rem; color: var(--ink-soft); }
.mu-mx-presets, .mu-ev-presets { display: flex; flex-wrap: wrap; gap: .4rem; margin-bottom: .8rem; }
.mu-mx-presets .mu-btn, .mu-ev-presets .mu-btn { padding: .4rem .8rem; font-size: .78rem; }
.mu-mix .mu-btn[aria-pressed="true"], .mu-env .mu-btn[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-mx-msg { margin: 1rem 0 0; min-height: 3.2em; font-size: .92rem; line-height: 1.6; }
.mu-mx-msg .zh, .mu-ev-msg .zh { display: block; color: var(--ink-soft); }
.mu-ev-ctl { display: grid; gap: .9rem; }
.mu-ev-ctl label { display: block; font-size: .82rem; font-weight: 700; }
.mu-ev-ctl label output { margin-left: .5rem; color: var(--brand-dk); font-variant-numeric: tabular-nums; }
.mu-ev-ctl input[type="range"] { display: block; width: 100%; margin-top: .3rem; accent-color: var(--brand); }
.mu-ev-msg { margin: 1rem 0 0; font-size: .92rem; line-height: 1.6; }

/* ── 哪一個波形？ ───────────────────────────────────────────────────── */
.mu-wh-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-which .mu-hg-sc { color: var(--ink-soft); }
.mu-which .mu-hg-score { color: var(--ink); }
.mu-which .mu-hg-nosound { background: #fff0ec; color: #8a3b24; }
.mu-wh-desc { margin: .8rem 0 0; padding: .6rem .9rem; border-radius: 10px; background: var(--cream); font-size: .92rem; }
.mu-wh-desc[hidden] { display: none; }
.mu-wh-desc .zh { display: block; color: var(--ink-soft); }
.mu-wh-opts { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .8rem; margin-top: 1rem; }
.mu-wh-opt { display: flex; flex-direction: column; gap: .4rem; padding: .6rem; border-radius: 14px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; text-align: left; transition: border-color .15s, transform .15s; }
.mu-wh-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-wh-opt canvas { width: 100%; height: 86px; display: block; border-radius: 8px; }
.mu-wh-name { font-size: .84rem; font-weight: 800; line-height: 1.35; }
.mu-wh-name .zh { display: block; font-weight: 600; color: var(--ink-soft); }
.mu-wh-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-wh-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-wh-opt:disabled:not(.is-right) { cursor: default; }
.mu-wh-msg { margin: 1rem 0 0; min-height: 3.4em; font-size: .94rem; line-height: 1.6; }
.mu-wh-msg .zh { display: block; color: var(--ink-soft); }
@media (max-width: 860px) { .mu-mx-grid, .mu-ev-grid { grid-template-columns: 1fr; } }
@media (max-width: 560px) {
  .mu-mix, .mu-env, .mu-which { padding: 1.1rem; }
  .mu-mx-row { grid-template-columns: 1.5rem minmax(0, 1fr) 3.6rem 2.4rem; gap: .35rem; font-size: .72rem; }
  .mu-wh-opts { grid-template-columns: 1fr; }
}

.al-lg-mode i { border-color: #7ef0e3; background: rgba(126,240,227,.25); height: 6px; border-radius: 3px; margin-top: .5rem; }
.al-lg-node i { border-color: #fff; background: #fff; width: 10px; height: 10px; margin: .3rem 4px 0; }

.mu-wh-opt:disabled { color: var(--ink); }

/* ── 第三課：節拍器 ─────────────────────────────────────────────────── */
.mu-bt-secline { margin: 0; font-size: .9rem; color: var(--al-text); }
.mu-bt-secline b { color: var(--al-sun); font-variant-numeric: tabular-nums; }
.mu-bt-secline .zh { display: block; color: var(--al-mute); }
.mu-presets-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.mu-meters { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.mu-meters button { line-height: 1.15; }
.mu-meters button small { display: block; font-family: var(--zh); font-size: .66rem; font-weight: 600; }
.mu-bt-lights { display: flex; gap: .55rem; justify-content: center; padding: .4rem 0; }
.mu-bt-dot { display: block; width: 26px; height: 26px; border-radius: 50%; background: #2b3550; border: 2px solid #4a5878; transition: background .05s, box-shadow .05s; }
.mu-bt-dot[hidden] { display: none; }
.mu-bt-dot.is-strong { border-color: #c9a14a; }
.mu-bt-dot.is-on { background: #7ef0e3; border-color: #fff; box-shadow: 0 0 16px 3px rgba(126,240,227,.6); }
.mu-bt-dot.is-strong.is-on { background: #ffd36e; box-shadow: 0 0 18px 4px rgba(255,211,110,.7); }
.mu-bt-bar { margin: 0; text-align: center; font-weight: 800; color: #fff; font-size: .9rem; }
.mu-bt-bar .zh { display: block; font-weight: 600; color: var(--al-mute); font-size: .8rem; }
.mu-bt-go[aria-pressed="true"] { background: transparent; color: var(--al-sun); }

/* 跟著拍 */
.mu-tap, .mu-meterq { margin-top: 1.5rem; padding: 1.5rem 1.6rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 940px; }
.mu-tp-top { display: flex; flex-wrap: wrap; justify-content: space-between; gap: .6rem 1rem; align-items: center; }
.mu-tp-speeds { display: flex; gap: .4rem; flex-wrap: wrap; }
.mu-tp-speeds .mu-btn[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-tp-stage { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 1.2rem; margin-top: 1.1rem; align-items: center; }
.mu-tp-drum { display: grid; place-items: center; min-height: 170px; border-radius: 50%; aspect-ratio: 1; max-width: 230px; margin: 0 auto; width: 100%; border: 6px solid #8a5a2b; background: radial-gradient(circle at 50% 40%, #fff8e3, #f1dfae); color: #5a3d17; font-family: var(--sans); font-weight: 800; font-size: 1.4rem; cursor: pointer; touch-action: manipulation; user-select: none; -webkit-user-select: none; transition: transform .06s, box-shadow .1s; }
.mu-tp-drum small { font-size: .74rem; font-weight: 700; color: #7a5a2e; }
.is-hit .mu-tp-drum { transform: scale(.96); box-shadow: 0 0 0 6px rgba(255,211,110,.5); }
.mu-tp-drum:focus-visible { outline: 3px solid var(--brand); outline-offset: 3px; }
.mu-tp-dots { display: flex; gap: .5rem; }
.mu-tp-dots i { width: 22px; height: 22px; border-radius: 50%; background: #e4e0d2; border: 2px solid #c9c2ac; }
.mu-tp-dots i.is-strong { border-color: var(--gold-dk); }
.mu-tp-dots i.is-on { background: var(--brand); border-color: var(--brand-dk); }
.mu-tp-dots i.is-strong.is-on { background: var(--gold); }
.mu-tp-count { margin: .5rem 0; font-family: var(--serif); font-size: 2.4rem; font-weight: 700; line-height: 1; color: var(--brand-dk); font-variant-numeric: tabular-nums; }
.is-counting .mu-tp-count { color: var(--gold-dk); }
.mu-tp-stats { margin: 0; display: grid; gap: .3rem; }
.mu-tp-stats div { display: flex; justify-content: space-between; gap: .6rem; font-size: .84rem; }
.mu-tp-stats dt { color: var(--ink-soft); }
.mu-tp-stats dd { margin: 0; font-weight: 800; font-variant-numeric: tabular-nums; }
.mu-tp-cv { display: block; width: 100%; height: 150px; margin-top: 1rem; border: 1px solid var(--line); border-radius: 12px; background: #fff; }
.mu-tp-msg { margin: .9rem 0 .5rem; min-height: 3.6em; font-size: .92rem; line-height: 1.6; }
.mu-tp-msg .zh { display: block; color: var(--ink-soft); }
.mu-tp-flash { color: var(--ink-soft); }

/* 這是幾拍子？ */
.mu-mt-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-meterq .mu-hg-sc { color: var(--ink-soft); }
.mu-meterq .mu-hg-score { color: var(--ink); }
.mu-meterq .mu-hg-nosound { background: #fff0ec; color: #8a3b24; }
.mu-mt-dots { display: flex; gap: .5rem; justify-content: center; margin-top: .8rem; }
.mu-mt-dots i { width: 18px; height: 18px; border-radius: 50%; background: #e4e0d2; border: 2px solid #c9c2ac; }
.mu-mt-dots i.is-on { background: var(--brand); border-color: var(--brand-dk); }
.mu-mt-desc { margin: .8rem 0 0; padding: .6rem .9rem; border-radius: 10px; background: var(--cream); font-size: .92rem; }
.mu-mt-desc[hidden] { display: none; }
.mu-mt-desc .zh { display: block; color: var(--ink-soft); }
.mu-mt-opts { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: .8rem; margin-top: 1rem; }
.mu-mt-opt { display: flex; flex-direction: column; align-items: center; gap: .3rem; padding: .9rem .4rem; border-radius: 14px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; transition: border-color .15s, transform .15s; color: var(--ink); }
.mu-mt-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-mt-opt b { font-family: var(--serif); font-size: 2rem; line-height: 1; }
.mu-mt-opt span { font-size: .84rem; font-weight: 800; text-align: center; }
.mu-mt-opt .zh { display: block; font-weight: 600; color: var(--ink-soft); }
.mu-mt-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-mt-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-mt-opt:disabled { cursor: default; }
.mu-mt-msg { margin: 1rem 0 0; min-height: 3.4em; font-size: .94rem; line-height: 1.6; }
.mu-mt-msg .zh { display: block; color: var(--ink-soft); }
@media (max-width: 760px) { .mu-tp-stage { grid-template-columns: 1fr; } }
@media (max-width: 560px) { .mu-tap, .mu-meterq { padding: 1.1rem; } .mu-tp-drum { max-width: 190px; min-height: 150px; } }

.al-lg-tick i.is-weight { border-color: #ffd36e; }

/* ── 第四課：力度與速度 ─────────────────────────────────────────────── */
.mu-cond { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #0c1428; color: #e8edf7; border-radius: 20px; box-shadow: var(--shadow); max-width: 1000px; }
.mu-cd-roll-w { border-radius: 12px; overflow: hidden; border: 1px solid rgba(160,180,230,.25); }
.mu-cd-roll { display: block; width: 100%; height: 210px; }
.mu-cd-reads { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: .8rem 1.2rem; margin-top: 1rem; }
.mu-cd-k { margin: 0 0 .2rem; font-size: .72rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: #ffd36e; }
.mu-cd-reads p:not(.mu-cd-k) { margin: 0; font-size: .92rem; line-height: 1.5; }
.mu-cd-reads b { font-size: 1.1rem; }
.mu-cd-reads i { font-style: normal; font-weight: 800; color: #7ef0e3; margin: 0 .2rem; }
.mu-cd-reads .zh, .mu-cd-note .zh { display: block; color: #9fb0cf; }
.mu-cd-note { margin-top: .4rem !important; font-size: .78rem !important; color: #9fb0cf; }
.mu-cd-note b { font-size: .8rem; color: #fff; }
.mu-cd-lad { margin-top: 1rem; }
.mu-cd-row6 { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: .4rem; }
.mu-cd-row3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: .4rem; max-width: 520px; }
.mu-cond button[aria-pressed]:not(.mu-cd-play) { padding: .55rem .2rem; border-radius: 12px; border: 1px solid rgba(160,180,230,.3); background: rgba(255,255,255,.05); color: #e8edf7; font-family: var(--sans); cursor: pointer; text-align: center; line-height: 1.2; }
.mu-cond button[aria-pressed]:not(.mu-cd-play) b { display: block; font-family: var(--serif); font-size: 1.25rem; }
.mu-cond button[aria-pressed]:not(.mu-cd-play) small { display: block; font-size: .66rem; font-weight: 600; color: #9fb0cf; margin-top: .15rem; }
.mu-cond button[aria-pressed]:not(.mu-cd-play):hover { background: rgba(255,255,255,.12); }
.mu-cond button[aria-pressed="true"]:not(.mu-cd-play) { border-color: #ffd36e; background: rgba(255,211,110,.16); box-shadow: 0 0 0 1px #ffd36e inset; }
.mu-cd-go { margin-top: 1.1rem; }
.mu-cond .mu-msg { margin-top: .9rem; min-height: 3.6em; color: #e8edf7; }
.mu-signq { margin-top: 1.5rem; padding: 1.5rem 1.6rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 940px; }
.mu-signq .mu-hg-sc { color: var(--ink-soft); }
.mu-signq .mu-hg-score { color: var(--ink); }
.mu-sg-k, .mu-tq-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-signq .mu-hg-nosound { background: #fff0ec; color: #8a3b24; }
.mu-q-desc { margin: .8rem 0 0; padding: .6rem .9rem; border-radius: 10px; background: var(--cream); font-size: .92rem; }
.mu-q-desc[hidden] { display: none; }
.mu-q-desc .zh, .mu-q-msg .zh { display: block; color: var(--ink-soft); }
.mu-q-msg { margin: 1rem 0 0; min-height: 3.4em; font-size: .94rem; line-height: 1.6; }
.mu-sg-opts { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: .7rem; margin-top: 1rem; }
.mu-tq-opts { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .8rem; margin-top: 1rem; }
.mu-sg-opt, .mu-tq-opt { display: flex; flex-direction: column; align-items: center; gap: .3rem; padding: .9rem .4rem; border-radius: 14px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); transition: border-color .15s, transform .15s; }
.mu-sg-opt:hover:not(:disabled), .mu-tq-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-sg-opt b { font-family: var(--serif); font-size: 1.25rem; }
.mu-tq-opt b { display: grid; place-items: center; width: 2.2rem; height: 2.2rem; border-radius: 50%; background: var(--gold); color: #1b1405; font-size: 1.1rem; }
.mu-sg-opt span, .mu-tq-opt span { font-size: .84rem; font-weight: 800; text-align: center; }
.mu-sg-opt .zh, .mu-tq-opt .zh { display: block; font-weight: 600; color: var(--ink-soft); }
.mu-sg-opt.is-right, .mu-tq-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-sg-opt.is-wrong, .mu-tq-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-sg-opt:disabled, .mu-tq-opt:disabled { cursor: default; color: var(--ink); }
.mu-tq-big { margin: 1rem 0 0; font-size: 1.15rem; font-weight: 700; }
.mu-tq-big .zh { display: block; font-size: .95rem; color: var(--ink-soft); font-weight: 600; }
.mu-tq-ladder { list-style: none; display: flex; flex-wrap: wrap; gap: .4rem; margin: .8rem 0 0; padding: 0; }
.mu-tq-ladder li { padding: .3rem .6rem; border-radius: 999px; background: var(--cream); border: 1px solid var(--line); font-size: .76rem; }
.mu-tq-ladder li b { margin-right: .3rem; }
.mu-tq-ladder li span { color: var(--ink-soft); }
.mu-tq-ladder li + li::before { content: none; }
@media (max-width: 760px) { .mu-cd-reads { grid-template-columns: 1fr; } .mu-sg-opts { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 560px) { .mu-cd-row6 { grid-template-columns: repeat(3, minmax(0, 1fr)); } .mu-cond, .mu-signq { padding: 1rem; } .mu-cd-roll { height: 170px; } .mu-tq-opts { grid-template-columns: 1fr; } }

/* ── 第五課：五線譜 ─────────────────────────────────────────────────── */
.mu-staffwrap { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-st-top { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: .6rem 1rem; }
.mu-st-clefs { display: flex; gap: .4rem; flex-wrap: wrap; }
.mu-st-clefs .mu-btn[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-st-help { margin: 0; font-size: .82rem; color: var(--ink-soft); }
.mu-st-grid { display: grid; grid-template-columns: minmax(0, 1.7fr) minmax(0, 1fr); gap: 1.2rem; margin-top: 1rem; align-items: stretch; }
.mu-st-cv, .mu-sq-cv { display: block; width: 100%; height: 260px; border: 1px solid var(--line); border-radius: 14px; background: #fffdf6; cursor: pointer; touch-action: none; }
.mu-st-cv:focus-visible { outline: 3px solid var(--brand); outline-offset: 2px; }
.mu-st-side { padding: 1rem 1.1rem; border-radius: 14px; background: var(--cream); border: 1px solid var(--line); }
.mu-st-k { margin: 0; font-size: .72rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; color: var(--gold-dk); }
.mu-st-k2 { margin-top: 1.1rem; }
.mu-st-name { margin: .3rem 0 0; font-family: var(--serif); font-size: 2.2rem; font-weight: 700; color: var(--brand-dk); line-height: 1.1; }
.mu-st-name span { font-family: var(--sans); font-size: 1.1rem; color: var(--ink-soft); font-weight: 700; }
.mu-st-hz { margin: .2rem 0 0; font-size: 1.15rem; font-weight: 800; font-variant-numeric: tabular-nums; }
.mu-st-hz small { color: var(--ink-soft); font-weight: 700; }
.mu-st-where { margin: .7rem 0 0; font-size: .92rem; font-weight: 700; line-height: 1.5; }
.mu-st-where .zh { display: block; font-weight: 500; color: var(--ink-soft); }
.mu-st-kb { display: grid; grid-template-columns: repeat(15, minmax(0, 1fr)); gap: 2px; margin-top: .5rem; }
.mu-st-key { height: 96px; padding: 0 0 .4rem; border: 1px solid #8e8570; border-radius: 0 0 6px 6px; background: linear-gradient(#fdfaf2, #fff 70%, #e9e3d2); display: flex; align-items: flex-end; justify-content: center; cursor: pointer; font-family: var(--sans); font-size: .76rem; font-weight: 800; color: #4a4636; }
.mu-st-key small { font-size: .6rem; margin-left: 1px; color: #8a8267; }
.mu-st-key.is-on { background: linear-gradient(#ffe9a8, #ffd36e); }
.mu-st-key:focus-visible { outline: 3px solid var(--brand); outline-offset: -3px; }
.mu-staffwrap .mu-msg { color: var(--ink); margin-top: .8rem; min-height: 3em; }
.mu-staffwrap .mu-msg .zh { color: var(--ink-soft); }
.mu-staffq { margin-top: 1.5rem; padding: 1.5rem 1.6rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 940px; }
.mu-staffq .mu-hg-sc { color: var(--ink-soft); } .mu-staffq .mu-hg-score { color: var(--ink); }
.mu-sq-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-sq-clef { margin: .8rem 0 .5rem; font-weight: 800; color: var(--brand-dk); }
.mu-sq-cv { height: 220px; cursor: default; }
.mu-sq-opts { display: grid; grid-template-columns: repeat(7, minmax(0, 1fr)); gap: .5rem; margin-top: 1rem; }
.mu-sq-opt { display: flex; flex-direction: column; align-items: center; padding: .7rem .2rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); transition: border-color .15s, transform .15s; }
.mu-sq-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-sq-opt b { font-family: var(--serif); font-size: 1.5rem; line-height: 1; }
.mu-sq-opt small { font-size: .68rem; color: var(--ink-soft); font-weight: 700; }
.mu-sq-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-sq-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-sq-opt:disabled { cursor: default; color: var(--ink); }
@media (max-width: 760px) { .mu-st-grid { grid-template-columns: 1fr; } }
@media (max-width: 560px) { .mu-staffwrap, .mu-staffq { padding: 1rem; } .mu-st-cv { height: 230px; } .mu-st-key { height: 78px; font-size: .64rem; } .mu-sq-opt b { font-size: 1.2rem; } .mu-sq-opts { gap: .3rem; } }

/* ── 第六課：音符積木 ───────────────────────────────────────────────── */
.mu-vals, .mu-beatq { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-vl-top { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; gap: .6rem 1rem; }
.mu-vl-ts { display: flex; align-items: center; gap: .4rem; flex-wrap: wrap; }
.mu-vl-ts .mu-st-k { margin-right: .3rem; }
.mu-vals .mu-btn[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-vals .mu-btn-gold { background: var(--gold); border-color: var(--gold); }
.mu-vl-count { margin: 0; font-family: var(--serif); font-size: 1.8rem; font-weight: 700; color: var(--brand-dk); font-variant-numeric: tabular-nums; }
.mu-vl-count small { font-family: var(--sans); font-size: .8rem; color: var(--ink-soft); font-weight: 700; }
.is-full .mu-vl-count { color: #2f9e63; }
.mu-vl-track { display: flex; gap: 3px; height: 54px; margin-top: .9rem; padding: 4px; border-radius: 12px; background: var(--cream); border: 1px dashed var(--line); transition: transform .08s; }
.is-full .mu-vl-track { border-style: solid; border-color: #2f9e63; background: #eefaf2; }
.is-shake .mu-vl-track { animation: mu-shake .3s; }
@keyframes mu-shake { 25% { transform: translateX(-6px); } 75% { transform: translateX(6px); } }
.mu-vl-blk { flex: var(--w) 1 0; min-width: 0; display: grid; place-items: center; border-radius: 8px; background: linear-gradient(#ffe08f, #ffd36e); border: 1px solid var(--gold-dk); color: #1b1405; font-size: .72rem; font-weight: 800; overflow: hidden; white-space: nowrap; padding: 0 2px; }
.mu-vl-blk.is-rest { background: repeating-linear-gradient(45deg, #e4e0d2, #e4e0d2 6px, #f4f1e6 6px, #f4f1e6 12px); border-color: #b9b29a; color: #6a6450; }
.mu-vl-empty { flex: var(--w) 1 0; border-radius: 8px; border: 1px dashed #c9c2ac; }
.mu-vl-cv { display: block; width: 100%; height: 220px; margin-top: .9rem; border: 1px solid var(--line); border-radius: 14px; background: #fffdf6; }
.mu-vl-vals { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: .4rem; margin-top: .4rem; }
.mu-vl-val { padding: .6rem .2rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); text-align: center; transition: border-color .15s, transform .15s, opacity .15s; }
.mu-vl-val:hover { border-color: var(--gold); transform: translateY(-2px); }
.mu-vl-val b { display: block; font-size: .86rem; }
.mu-vl-val small { display: block; font-size: .68rem; color: var(--ink-soft); font-weight: 700; margin-top: .15rem; }
.mu-vl-val.is-nofit { opacity: .45; }
.mu-vl-mods { display: flex; flex-wrap: wrap; gap: .4rem; margin-top: .8rem; }
.mu-vals .mu-msg { color: var(--ink); margin-top: .8rem; min-height: 3em; }
.mu-vals .mu-msg .zh { color: var(--ink-soft); }
.mu-beatq .mu-hg-sc { color: var(--ink-soft); } .mu-beatq .mu-hg-score { color: var(--ink); }
.mu-bq-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-bq-name { margin: .8rem 0 .4rem; font-weight: 800; color: var(--brand-dk); }
.mu-bq-name .zh { font-weight: 600; color: var(--ink-soft); }
.mu-bq-cv { display: block; width: 100%; height: 200px; border: 1px solid var(--line); border-radius: 14px; background: #fffdf6; }
.mu-bq-opts { display: grid; grid-template-columns: repeat(7, minmax(0, 1fr)); gap: .4rem; margin-top: 1rem; }
.mu-bq-opt { display: flex; flex-direction: column; align-items: center; padding: .6rem .1rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); transition: border-color .15s, transform .15s; }
.mu-bq-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-bq-opt b { font-family: var(--serif); font-size: 1.5rem; line-height: 1.1; }
.mu-bq-opt small { font-size: .6rem; color: var(--ink-soft); font-weight: 700; text-align: center; }
.mu-bq-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-bq-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-bq-opt:disabled { cursor: default; color: var(--ink); }
.mu-split { margin-top: 1.5rem; padding: 1.2rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 900px; display: grid; gap: .5rem; }
.mu-sp-row { display: grid; grid-template-columns: 9.5rem minmax(0, 1fr); gap: .8rem; align-items: center; padding: .3rem .5rem; border-radius: 12px; border: 1px solid transparent; background: transparent; font-family: var(--sans); cursor: pointer; text-align: left; color: var(--ink); }
.mu-sp-row:hover, .mu-sp-row.is-on { border-color: var(--gold); background: #fff8e6; }
.mu-sp-name { font-size: .86rem; font-weight: 800; }
.mu-sp-name small { display: block; font-size: .72rem; font-weight: 600; color: var(--ink-soft); }
.mu-sp-bar { position: relative; display: flex; gap: 2px; height: 30px; }
.mu-sp-bar i { flex: 1 1 0; border-radius: 4px; background: linear-gradient(#ffe08f, #ffd36e); border: 1px solid var(--gold-dk); }
.mu-sp-head { position: absolute; left: 0; top: 0; bottom: 0; width: 0; background: rgba(13,157,140,.28); border-right: 3px solid #0d9d8c; border-radius: 4px; pointer-events: none; }
.mu-sp-note { margin: .4rem 0 0; font-size: .8rem; color: var(--ink-soft); }
@media (max-width: 560px) { .mu-vals, .mu-beatq, .mu-split { padding: 1rem; } .mu-vl-vals { grid-template-columns: repeat(2, minmax(0, 1fr)); } .mu-bq-opts { grid-template-columns: repeat(4, minmax(0, 1fr)); } .mu-sp-row { grid-template-columns: 6.2rem minmax(0, 1fr); } .mu-vl-cv { height: 190px; } }

/* ── 第七課：音階 ─────────────────────────────────────────────────── */
.mu-scl, .mu-tune, .mu-scaleq { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-scl .mu-btn[aria-pressed="true"], .mu-tune .mu-btn[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-scl .mu-btn-gold, .mu-tune .mu-btn-gold { background: var(--gold); border-color: var(--gold); }
.mu-scl .mu-msg, .mu-tune .mu-tn-msg, .mu-scaleq .mu-q-msg { color: var(--ink); margin-top: .8rem; min-height: 3.4em; font-size: .86rem; line-height: 1.6; }
.mu-scl .mu-msg .zh, .mu-tune .mu-tn-msg .zh, .mu-scaleq .mu-q-msg .zh { display: block; color: var(--ink-soft); }
.mu-sc-row { display: flex; align-items: center; flex-wrap: wrap; gap: .4rem; margin-top: .6rem; }
.mu-sc-row:first-child { margin-top: 0; }
.mu-sc-row .mu-st-k { margin-right: .3rem; }
.mu-sc-steps { display: flex; flex-wrap: wrap; align-items: center; gap: 4px; min-height: 58px; margin-top: .9rem; padding: .5rem; border-radius: 12px; background: var(--cream); border: 1px dashed var(--line); }
.is-done .mu-sc-steps { border-style: solid; border-color: #2f9e63; background: #eefaf2; }
.is-shake .mu-sc-steps { animation: mu-shake .3s; }
.mu-sc-note { display: grid; place-items: center; min-width: 2.6rem; padding: .25rem .4rem; border-radius: 10px; background: linear-gradient(#ffe08f, #ffd36e); border: 1px solid var(--gold-dk); line-height: 1.1; }
.mu-sc-note b { font-family: var(--serif); font-size: 1.1rem; }
.mu-sc-note small { font-size: .62rem; color: #6a5300; font-weight: 800; }
.mu-sc-note.is-root { background: linear-gradient(#bff0e8, #7ef0e3); border-color: #0d9d8c; }
.mu-sc-note.is-play { outline: 3px solid #0d9d8c; }
.mu-sc-note.is-next { background: transparent; border-style: dashed; border-color: #c9c2ac; color: #8a8267; }
.mu-sc-gap { display: grid; place-items: center; min-width: 1.5rem; padding: .15rem .3rem; border-radius: 999px; font-size: .74rem; font-weight: 800; background: #e8eefc; border: 1px solid #aab8dd; color: #2a3a6b; }
.mu-sc-gap.g1 { background: #fde3e3; border-color: #e0a0a0; color: #7a2a2a; }
.mu-sc-gap.g3 { background: #e5f3d9; border-color: #a9cf8e; color: #35591d; }
.mu-sc-gap.g0 { background: transparent; border-style: dashed; color: #8a8267; }
.mu-sc-pat { margin: .8rem 0 0; display: flex; flex-wrap: wrap; align-items: center; gap: .35rem; }
.mu-sc-pg { display: inline-grid; place-items: center; min-width: 2rem; height: 1.7rem; padding: 0 .4rem; border-radius: 999px; font-size: .78rem; font-weight: 800; background: #e8eefc; border: 1px solid #aab8dd; color: #2a3a6b; opacity: .55; }
.mu-sc-pg.g1 { background: #fde3e3; border-color: #e0a0a0; color: #7a2a2a; }
.mu-sc-pg.g3 { background: #e5f3d9; border-color: #a9cf8e; color: #35591d; }
.mu-sc-pg.is-done { opacity: 1; }
.mu-sc-pg.is-next { opacity: 1; outline: 2px solid var(--brand); }
.mu-scq-pat .mu-sc-pg, .mu-sqz-pat .mu-sc-pg { opacity: 1; }
.mu-sc-cv, .mu-tn-cv { display: block; width: 100%; height: 200px; margin-top: .9rem; border: 1px solid var(--line); border-radius: 14px; background: #fffdf6; }
.mu-sc-kb { position: relative; height: 128px; margin-top: .9rem; user-select: none; }
.mu-sc-key { position: absolute; top: 0; padding: 0; border: 1px solid #8e8570; cursor: pointer; font-family: var(--sans); }
.mu-sc-key.is-white { height: 100%; border-radius: 0 0 6px 6px; background: linear-gradient(#fdfaf2, #fff 70%, #e9e3d2); z-index: 1; }
.mu-sc-key.is-black { height: 62%; border-radius: 0 0 4px 4px; background: linear-gradient(#3a352a, #1b1a15); border-color: #111; z-index: 2; }
.mu-sc-key.is-white.is-on { background: linear-gradient(#ffe9a8, #ffd36e); }
.mu-sc-key.is-black.is-on { background: linear-gradient(#e0a92a, #b98100); }
.mu-sc-key.is-root { box-shadow: inset 0 -6px 0 #0d9d8c; }
.mu-sc-key.is-play { outline: 3px solid #0d9d8c; outline-offset: -3px; z-index: 3; }
.mu-sc-key:focus-visible { outline: 3px solid var(--brand); outline-offset: -3px; z-index: 4; }
.mu-sc-btns { display: flex; flex-wrap: wrap; gap: .4rem; margin-top: .8rem; }
.mu-tn-names { margin: .7rem 0 0; font-family: var(--serif); font-size: 1.2rem; font-weight: 700; color: var(--brand-dk); }
.mu-scq-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-scq-opts { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: .5rem; margin-top: 1rem; }
.mu-scq-opt { display: flex; flex-direction: column; align-items: center; padding: .8rem .3rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); transition: transform .12s, border-color .12s; }
.mu-scq-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-scq-opt b { font-family: var(--serif); font-size: 1.15rem; line-height: 1.1; }
.mu-scq-opt small { font-size: .72rem; color: var(--ink-soft); font-weight: 700; }
.mu-scq-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-scq-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-scq-opt:disabled { cursor: default; color: var(--ink); }
.mu-scaleq .mu-hg-sc { color: var(--ink-soft); }
.mu-sqz-pat { margin: .8rem 0 0; display: flex; flex-wrap: wrap; align-items: center; gap: .35rem; }
@media (max-width: 560px) { .mu-scl, .mu-tune, .mu-scaleq { padding: 1rem; } .mu-sc-kb { height: 108px; } .mu-sc-cv, .mu-tn-cv { height: 180px; } .mu-sc-note { min-width: 2.2rem; } }

/* ── 第八課：兩個音一起響、和弦 ───────────────────────────────────── */
.mu-hm, .mu-chord, .mu-chordq { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-hm .mu-btn[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-hm .mu-btn-gold, .mu-chord .mu-btn-gold, .mu-chordq .mu-btn-gold { background: var(--gold); border-color: var(--gold); }
.mu-hm .mu-msg, .mu-chord .mu-ch-msg, .mu-chordq .mu-q-msg { color: var(--ink); margin: .8rem 0 0; min-height: 3.4em; font-size: .86rem; line-height: 1.6; }
.mu-hm .mu-msg .zh, .mu-chord .mu-ch-msg .zh, .mu-chordq .mu-q-msg .zh { display: block; color: var(--ink-soft); }
.mu-hm-cv, .mu-hm-cvb { display: block; width: 100%; height: 230px; margin-top: .9rem; border: 1px solid var(--line); border-radius: 14px; background: #fffdf6; }
.mu-hm-cvb { height: 110px; margin-top: .6rem; }
.mu-hm-read { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: .6rem; margin-top: .9rem; }
.mu-hm-read > div { padding: .6rem .8rem; border-radius: 12px; background: var(--cream); border: 1px solid var(--line); }
.mu-hm-read b, .mu-hm-read p { margin: 0; font-family: var(--serif); font-size: 1.15rem; font-weight: 700; color: var(--brand-dk); font-variant-numeric: tabular-nums; }
.mu-hm-read small { display: block; font-family: var(--sans); font-size: .68rem; color: var(--ink-soft); font-weight: 700; }
.mu-hm-mis-row { display: flex; flex-wrap: wrap; align-items: center; gap: .6rem 1rem; margin-top: .9rem; }
.mu-hm-mis { flex: 1 1 220px; max-width: 420px; accent-color: var(--brand); }
.mu-hm-mis-v { font-weight: 800; font-variant-numeric: tabular-nums; min-width: 9rem; }
.mu-ch-name { margin: .9rem 0 0; font-family: var(--serif); font-size: 1.35rem; font-weight: 700; color: var(--brand-dk); }
.mu-ch-name small { display: block; font-family: var(--sans); font-size: .76rem; font-weight: 700; color: var(--ink-soft); }
.mu-cq-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-cq-opts { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .5rem; margin-top: 1rem; }
.mu-cq-opt { display: flex; flex-direction: column; align-items: center; padding: .8rem .3rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); transition: transform .12s, border-color .12s; }
.mu-cq-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-cq-opt b { font-family: var(--serif); font-size: 1.15rem; line-height: 1.1; }
.mu-cq-opt small { font-size: .72rem; color: var(--ink-soft); font-weight: 700; }
.mu-cq-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-cq-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-cq-opt:disabled { cursor: default; color: var(--ink); }
.mu-chordq .mu-hg-sc { color: var(--ink-soft); }
.mu-cq-pat { margin: .8rem 0 0; display: flex; flex-wrap: wrap; align-items: center; gap: .35rem; }
.mu-cq-pat .mu-sc-pg { opacity: 1; }
@media (max-width: 560px) { .mu-hm, .mu-chord, .mu-chordq { padding: 1rem; } .mu-hm-cv { height: 210px; } }
.mu-hm-read .mu-st-k { display: block; margin-bottom: .2rem; }
.mu-hm-read b { display: block; }

/* ── 第九課：樂器怎麼發出聲音 ─────────────────────────────────────── */
.mu-fams { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: .4rem; margin-top: .4rem; }
.mu-fams button { display: flex; flex-direction: column; align-items: flex-start; padding: .45rem .6rem; border-radius: 12px; border: 1px solid rgba(255,255,255,.18); background: rgba(255,255,255,.06); color: inherit; font-family: var(--sans); cursor: pointer; text-align: left; }
.mu-fams button b { font-size: .9rem; }
.mu-fams button small { font-size: .7rem; opacity: .75; }
.mu-fams button[aria-pressed="true"] { border-color: var(--al-sun); background: rgba(255,211,110,.16); }
.mu-fam-card { margin-top: .8rem; }
.mu-fam-card .al-sky-k small { text-transform: none; letter-spacing: 0; opacity: .8; font-weight: 600; }
.mu-fam-dl { margin: .4rem 0 0; font-size: .8rem; line-height: 1.5; }
.mu-fam-dl dt { margin-top: .5rem; font-size: .66rem; font-weight: 800; letter-spacing: .06em; text-transform: uppercase; color: var(--al-sun); }
.mu-fam-dl dd { margin: .1rem 0 0; }
.mu-fam-dl dd .zh { display: block; opacity: .75; }
.mu-fam-ratio { font-family: var(--serif); font-size: 1rem; font-weight: 700; font-variant-numeric: tabular-nums; }
.mu-pitchup, .mu-famq { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-pu-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: .8rem; }
.mu-pu { padding: .8rem .9rem; border-radius: 14px; background: var(--cream); border: 1px solid var(--line); }
.mu-pu-h { margin: 0 0 .5rem; font-size: .9rem; }
.mu-pu-h span { color: var(--ink-soft); font-weight: 600; }
.mu-pu .mu-slide { display: block; font-size: .76rem; font-weight: 700; color: var(--ink-soft); }
.mu-pu input[type=range] { width: 100%; margin-top: .3rem; accent-color: var(--brand); }
.mu-pu-out { margin: .5rem 0 0; font-variant-numeric: tabular-nums; }
.mu-pu-out b { font-family: var(--serif); font-size: 1.15rem; color: var(--brand-dk); }
.mu-pu-out small { display: block; color: var(--ink-soft); font-weight: 700; }
.mu-pu-law { margin: .3rem 0 .6rem; font-size: .76rem; color: var(--ink-soft); }
.mu-fq-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-fq-opts { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: .5rem; margin-top: 1rem; }
.mu-fq-opt { display: flex; flex-direction: column; align-items: center; padding: .8rem .2rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); transition: transform .12s, border-color .12s; }
.mu-fq-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-fq-opt b { font-size: .92rem; }
.mu-fq-opt small { font-size: .72rem; color: var(--ink-soft); font-weight: 700; }
.mu-fq-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-fq-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-fq-opt:disabled { cursor: default; color: var(--ink); }
.mu-famq .mu-hg-sc { color: var(--ink-soft); }
.mu-famq .mu-q-msg { color: var(--ink); margin: .8rem 0 0; min-height: 3.4em; font-size: .86rem; line-height: 1.6; }
.mu-famq .mu-q-msg .zh { display: block; color: var(--ink-soft); }
.mu-famq .mu-btn-gold, .mu-pitchup .mu-btn { background: #fff; }
.mu-famq .mu-btn-gold { background: var(--gold); border-color: var(--gold); }
.mu-fq-pat { margin: .8rem 0 0; }
.mu-fq-pat b { font-family: var(--serif); font-size: 1.1rem; color: var(--brand-dk); }
@media (max-width: 560px) { .mu-pitchup, .mu-famq { padding: 1rem; } .mu-fq-opts { grid-template-columns: repeat(2, minmax(0, 1fr)); } }

/* ── 第十課：鋼琴裡面 ───────────────────────────────────────────── */
.mu-aside .mu-pi-vel { width: 100%; accent-color: var(--al-sun); }
.mu-pi-velout { font-family: var(--serif); font-size: 1.05rem; color: var(--al-sun); text-transform: none; font-style: italic; }
.mu-pi-press { width: 100%; margin-top: .6rem; touch-action: none; user-select: none; }
.mu-aside [data-pedal] { width: 100%; margin-top: .4rem; }
.mu-aside [data-pedal][aria-pressed="true"] { border-color: var(--al-sun); background: rgba(255,211,110,.28); }
.mu-pi-read { margin: .5rem 0 0; font-family: var(--serif); font-size: 1.05rem; font-weight: 700; font-variant-numeric: tabular-nums; }
.mu-pi-read small { display: block; font-family: var(--sans); font-size: .68rem; font-weight: 600; opacity: .75; }
.mu-pi-brt i { display: block; height: 8px; border-radius: 4px; background: linear-gradient(90deg, #7ef0e3, #ffd36e); width: calc(var(--w) * 100%); transition: width .2s; }
.mu-pi-stage { margin: .7rem 0 0; padding: 0; list-style: none; font-size: .78rem; line-height: 1.4; }
.mu-pi-stage li { padding: .25rem .4rem; border-left: 3px solid rgba(255,255,255,.18); opacity: .6; }
.mu-pi-stage li b { color: var(--al-sun); margin-right: .2rem; }
.mu-pi-stage li .zh { display: block; opacity: .8; }
.mu-pi-stage li.is-on { opacity: 1; border-left-color: var(--al-sun); background: rgba(255,211,110,.1); }
.mu-stretch, .mu-partq { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-stretch .mu-slide { display: block; font-size: .8rem; font-weight: 700; color: var(--ink-soft); }
.mu-stretch input[type=range] { width: 100%; max-width: 420px; display: block; margin-top: .3rem; accent-color: var(--brand); }
.mu-st-out { margin: .7rem 0 0; }
.mu-st-out b { font-family: var(--serif); font-size: 1.3rem; color: var(--brand-dk); }
.mu-st-out small { display: block; color: var(--ink-soft); font-weight: 700; }
.mu-st-tbl { margin-top: .7rem; border-collapse: collapse; font-size: .82rem; font-variant-numeric: tabular-nums; }
.mu-st-tbl th, .mu-st-tbl td { padding: .25rem .7rem; border-bottom: 1px solid var(--line); text-align: right; }
.mu-st-tbl th { color: var(--gold-dk); font-size: .7rem; letter-spacing: .04em; }
.mu-stretch .mu-q-msg, .mu-partq .mu-q-msg { color: var(--ink); margin: .8rem 0 0; min-height: 3.4em; font-size: .86rem; line-height: 1.6; }
.mu-stretch .mu-q-msg .zh, .mu-partq .mu-q-msg .zh { display: block; color: var(--ink-soft); }
.mu-stretch .mu-btn-gold, .mu-partq .mu-btn-gold { background: var(--gold); border-color: var(--gold); }
.mu-pq-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-pq-fn { margin: .9rem 0 0; font-size: 1.05rem; line-height: 1.5; }
.mu-pq-fn .zh { display: block; font-weight: 600; color: var(--ink-soft); }
.mu-pq-opts { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: .5rem; margin-top: 1rem; }
.mu-pq-opt { display: flex; flex-direction: column; align-items: center; padding: .8rem .2rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); transition: transform .12s, border-color .12s; }
.mu-pq-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-pq-opt b { font-size: .92rem; }
.mu-pq-opt small { font-size: .72rem; color: var(--ink-soft); font-weight: 700; }
.mu-pq-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-pq-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-pq-opt:disabled { cursor: default; color: var(--ink); }
.mu-partq .mu-hg-sc { color: var(--ink-soft); }
@media (max-width: 560px) { .mu-stretch, .mu-partq { padding: 1rem; } .mu-pq-opts { grid-template-columns: repeat(2, minmax(0, 1fr)); } }

/* ── 第十一課：交響樂團怎麼坐 ───────────────────────────────────── */
.mu-or-all { width: 100%; margin-top: .6rem; }
.mu-aside .mu-k2 { margin-top: .9rem; }
.mu-mixer, .mu-seatq { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-mx-head { margin: 0 0 .6rem; }
.mu-mx-head b { font-family: var(--serif); font-size: 1.2rem; color: var(--brand-dk); margin-left: .4rem; }
.mu-mx-row { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: .5rem; }
.mu-mx-b { display: flex; flex-direction: column; align-items: flex-start; gap: .1rem; padding: .7rem .8rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); text-align: left; }
.mu-mx-b b { font-size: .92rem; }
.mu-mx-b small { font-size: .72rem; color: var(--ink-soft); font-weight: 700; }
.mu-mx-b[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-mx-bar { display: block; width: 100%; height: 8px; margin-top: .4rem; border-radius: 4px; background: var(--cream); overflow: hidden; }
.mu-mx-bar i { display: block; height: 100%; width: calc(var(--w, 0) * 100%); background: linear-gradient(90deg, #7ef0e3, #ffd36e); transition: width .2s; }
.mu-mixer .mu-q-msg, .mu-seatq .mu-q-msg { color: var(--ink); margin: .8rem 0 0; min-height: 3.4em; font-size: .86rem; line-height: 1.6; }
.mu-mixer .mu-q-msg .zh, .mu-seatq .mu-q-msg .zh { display: block; color: var(--ink-soft); }
.mu-mixer .mu-btn-gold, .mu-seatq .mu-btn-gold { background: var(--gold); border-color: var(--gold); }
.mu-sq2-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-sq2-what { margin: .9rem 0 0; font-size: 1.05rem; line-height: 1.5; }
.mu-sq2-what .zh { font-weight: 600; color: var(--ink-soft); }
.mu-sq2-what small { display: block; font-size: .76rem; color: var(--ink-soft); font-weight: 700; margin-top: .2rem; }
.mu-sq2-opts { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: .5rem; margin-top: 1rem; }
.mu-sq2-opt { display: flex; flex-direction: column; align-items: center; padding: .8rem .2rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); transition: transform .12s, border-color .12s; }
.mu-sq2-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-sq2-opt b { font-size: .9rem; }
.mu-sq2-opt small { font-size: .72rem; color: var(--ink-soft); font-weight: 700; }
.mu-sq2-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-sq2-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-sq2-opt:disabled { cursor: default; color: var(--ink); }
.mu-seatq .mu-hg-sc { color: var(--ink-soft); }
@media (max-width: 560px) { .mu-mixer, .mu-seatq { padding: 1rem; } .mu-mx-row, .mu-sq2-opts { grid-template-columns: repeat(2, minmax(0, 1fr)); } }

/* ── 第十二課：國樂器 ───────────────────────────────────────────── */
.mu-wayq, .mu-penta { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-wq-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-wq-opts { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: .5rem; margin-top: 1rem; }
.mu-wq-opt { display: flex; flex-direction: column; align-items: center; padding: .8rem .2rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); transition: transform .12s, border-color .12s; }
.mu-wq-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-wq-opt b { font-family: var(--serif); font-size: 1.6rem; line-height: 1.1; }
.mu-wq-opt small { font-size: .74rem; color: var(--ink-soft); font-weight: 700; }
.mu-wq-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-wq-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-wq-opt:disabled { cursor: default; color: var(--ink); }
.mu-wq-hint { margin: .8rem 0 0; font-size: .86rem; line-height: 1.6; }
.mu-wq-hint .zh { display: block; color: var(--ink-soft); }
.mu-wayq .mu-hg-sc { color: var(--ink-soft); }
.mu-wayq .mu-q-msg, .mu-penta .mu-q-msg { color: var(--ink); margin: .8rem 0 0; min-height: 3.4em; font-size: .86rem; line-height: 1.6; }
.mu-wayq .mu-q-msg .zh, .mu-penta .mu-q-msg .zh { display: block; color: var(--ink-soft); }
.mu-wayq .mu-btn-gold, .mu-penta .mu-btn-gold { background: var(--gold); border-color: var(--gold); }
.mu-penta .mu-btn[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-pn-row { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: .5rem; margin-top: .9rem; }
.mu-pn-key { display: flex; flex-direction: column; align-items: center; padding: 1.1rem .2rem; border-radius: 12px; border: 1px solid var(--line); background: linear-gradient(#fff, #f6efd9); font-family: var(--sans); cursor: pointer; color: var(--ink); transition: transform .12s; }
.mu-pn-key:hover { transform: translateY(-2px); border-color: var(--gold); }
.mu-pn-key b { font-family: var(--serif); font-size: 1.7rem; line-height: 1; }
.mu-pn-key small { font-size: .7rem; color: var(--ink-soft); font-weight: 700; margin-top: .25rem; }
.mu-pn-key.is-on { background: linear-gradient(#ffe9a8, #ffd36e); border-color: var(--gold-dk); }
@media (max-width: 560px) { .mu-wayq, .mu-penta { padding: 1rem; } .mu-wq-opts { grid-template-columns: repeat(2, minmax(0, 1fr)); } .mu-pn-row { grid-template-columns: repeat(3, minmax(0, 1fr)); } }

/* ── 第十三課：西洋古典音樂四百年 ───────────────────────────────── */
.mu-eras, .mu-eraq, .mu-timeline { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-eras .mu-btn[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-eras .mu-btn-gold, .mu-eraq .mu-btn-gold { background: var(--gold); border-color: var(--gold); }
.mu-er-info { margin: .8rem 0 0; font-size: .9rem; }
.mu-er-info small { color: var(--ink-soft); font-weight: 700; margin-left: .4rem; }
.mu-er-cv { display: block; width: 100%; height: 260px; margin-top: .6rem; border: 1px solid var(--line); border-radius: 14px; background: #fffdf6; }
.mu-er-fh { margin-top: 1rem; }
.mu-er-feats { margin: .3rem 0 0; padding-left: 1.2rem; font-size: .88rem; line-height: 1.6; }
.mu-er-feats[hidden] { display: none; }
.mu-er-feats .zh, .mu-eq-hint .zh, .mu-tl-notes .zh, .mu-tl-caveat .zh { display: block; color: var(--ink-soft); }
.mu-eras .mu-msg, .mu-eraq .mu-q-msg { color: var(--ink); margin: .8rem 0 0; min-height: 3.4em; font-size: .86rem; line-height: 1.6; }
.mu-eras .mu-msg .zh, .mu-eraq .mu-q-msg .zh { display: block; color: var(--ink-soft); }
.mu-eq-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-eq-opts { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: .5rem; margin-top: 1rem; }
.mu-eq-opt { display: flex; flex-direction: column; align-items: center; padding: .8rem .2rem; border-radius: 12px; border: 1px solid var(--line); background: #fff; font-family: var(--sans); cursor: pointer; color: var(--ink); transition: transform .12s, border-color .12s; }
.mu-eq-opt:hover:not(:disabled) { border-color: var(--gold); transform: translateY(-2px); }
.mu-eq-opt b { font-family: var(--serif); font-size: 1.15rem; }
.mu-eq-opt small { font-size: .74rem; color: var(--ink-soft); font-weight: 700; }
.mu-eq-opt.is-right { border-color: #2f9e63; background: #eefaf2; }
.mu-eq-opt.is-wrong { border-color: #e08a8a; background: #fdf0f0; opacity: .7; }
.mu-eq-opt:disabled { cursor: default; color: var(--ink); }
.mu-eq-hint { margin: .8rem 0 0; font-size: .86rem; }
.mu-eq-hint ul { margin: .3rem 0 0; padding-left: 1.2rem; line-height: 1.6; }
.mu-eraq .mu-hg-sc { color: var(--ink-soft); }
.mu-tl-axis { position: relative; height: 1.4rem; margin: 0 0 .3rem; font-size: .7rem; color: var(--ink-soft); font-weight: 700; }
.mu-tl-axis span { position: absolute; left: var(--l); transform: translateX(-50%); }
.mu-tl-bars { position: relative; height: 4.2rem; border-radius: 12px; background: var(--cream); border: 1px solid var(--line); }
.mu-tl-bar { position: absolute; left: var(--l); width: var(--w); top: .5rem; bottom: .5rem; padding: .3rem .5rem; border-radius: 8px; background: var(--c); border: 1px solid rgba(0,0,0,.12); overflow: hidden; line-height: 1.25; }
.mu-tl-bar b { display: block; font-size: .8rem; }
.mu-tl-bar small { font-size: .66rem; font-weight: 700; opacity: .8; }
.mu-tl-notes { margin: 1rem 0 0; padding-left: 1.2rem; font-size: .86rem; line-height: 1.6; }
.mu-tl-caveat { margin: .8rem 0 0; font-size: .8rem; color: var(--ink-soft); }
@media (max-width: 560px) { .mu-eras, .mu-eraq, .mu-timeline { padding: 1rem; } .mu-eq-opts { grid-template-columns: 1fr; } .mu-er-cv { height: 220px; } .mu-tl-bar small { display: none; } }

/* ── 第十四課：爵士與搖擺 ───────────────────────────────────────── */
.mu-swing, .mu-swingq, .mu-improv { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-swing .mu-btn[aria-pressed="true"], .mu-improv .mu-btn[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-swing .mu-btn-gold, .mu-swingq .mu-btn-gold, .mu-improv .mu-btn-gold { background: var(--gold); border-color: var(--gold); }
.mu-sw-sliders { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; margin-top: .9rem; }
.mu-sw-lab { display: flex; flex-direction: column; gap: .35rem; font-size: .84rem; font-weight: 700; }
.mu-sw-lab input[type=range] { width: 100%; accent-color: var(--brand); }
.mu-sw-info { margin: .8rem 0 0; font-size: .9rem; }
.mu-sw-info small { display: block; color: var(--ink-soft); font-weight: 700; margin-top: .15rem; }
.mu-sw-cv { display: block; width: 100%; height: 240px; margin-top: .6rem; border: 1px solid var(--line); border-radius: 14px; background: #fffdf6; }
.mu-swing .mu-msg, .mu-swingq .mu-q-msg, .mu-improv .mu-msg { color: var(--ink); margin: .8rem 0 0; min-height: 3.4em; font-size: .86rem; line-height: 1.6; }
.mu-swing .mu-msg .zh, .mu-swingq .mu-q-msg .zh, .mu-improv .mu-msg .zh { display: block; color: var(--ink-soft); }
.mu-sq-k { margin: 0; font-size: .78rem; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; color: var(--gold-dk); }
.mu-swingq .mu-eq-opts { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.mu-swingq .mu-hg-sc { color: var(--ink-soft); }
.mu-im-log { margin: .8rem 0 0; min-height: 2.2em; font-size: .82rem; line-height: 2; }
.mu-im-chip { display: inline-block; padding: .05rem .5rem; border-radius: 999px; background: #f1e9fb; border: 1px solid #d9c6f0; font-weight: 700; }
.mu-im-empty { color: var(--ink-soft); }
.mu-im-note { min-width: 3.2rem; }
@media (max-width: 560px) { .mu-swing, .mu-swingq, .mu-improv { padding: 1rem; } .mu-sw-sliders { grid-template-columns: 1fr; } .mu-sw-cv { height: 210px; } }

/* ── 第十五課：聲部怎麼疊 ───────────────────────────────────────── */
.mu-layers, .mu-layerq { margin-top: 1.5rem; padding: 1.3rem 1.4rem; background: #fff; border: 1px solid var(--line); border-radius: 20px; box-shadow: var(--shadow-sm); max-width: 1000px; }
.mu-layers .mu-btn[aria-pressed="true"] { border-color: var(--brand); background: var(--brand-lt); }
.mu-layers .mu-btn-gold, .mu-layerq .mu-btn-gold { background: var(--gold); border-color: var(--gold); }
.mu-ly-info { margin: .8rem 0 0; font-size: .9rem; }
.mu-ly-info small { display: block; color: var(--ink-soft); font-weight: 700; margin-top: .15rem; }
.mu-layers .mu-msg, .mu-layerq .mu-q-msg { color: var(--ink); margin: .8rem 0 0; min-height: 3.4em; font-size: .86rem; line-height: 1.6; }
.mu-layers .mu-msg .zh, .mu-layerq .mu-q-msg .zh { display: block; color: var(--ink-soft); }
.mu-layerq .mu-hg-sc { color: var(--ink-soft); }
.mu-ly-opts { grid-template-columns: repeat(4, minmax(0, 1fr)); }
@media (max-width: 560px) { .mu-layers, .mu-layerq { padding: 1rem; } .mu-ly-opts { grid-template-columns: repeat(2, minmax(0, 1fr)); } }