/* =========================================================
   前台首页样式 site.css
   ========================================================= */

/* ---------------- Header ---------------- */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  transition: background .3s, box-shadow .3s, padding .3s;
  padding: 16px 0;
}
.site-header.is-stuck {
  background: rgba(253, 248, 241, .88);
  backdrop-filter: saturate(180%) blur(14px);
  box-shadow: 0 1px 0 var(--line), 0 6px 24px rgba(92,61,38,.06);
  padding: 10px 0;
}
.nav { display: flex; align-items: center; gap: 28px; }
.logo { display: flex; align-items: center; gap: 11px; font-weight: 900; font-size: 19px; color: var(--wood-deep); letter-spacing: -.02em; }
.logo-mark {
  width: 40px; height: 40px; border-radius: 13px; flex: none;
  background: linear-gradient(140deg, var(--wood-light), var(--wood) 60%, var(--wood-dark));
  display: grid; place-items: center; box-shadow: 0 6px 16px rgba(139,94,60,.3);
  position: relative; overflow: hidden;
}
.logo-mark::after {
  content: ""; position: absolute; inset: 0;
  background: repeating-linear-gradient(90deg, transparent 0 6px, rgba(255,255,255,.16) 6px 7px);
}
.logo-mark span { position: relative; z-index: 1; color: #fff; font-size: 19px; }
.logo small { display: block; font-size: 10.5px; font-weight: 600; letter-spacing: .22em; color: var(--wood-light); }

.nav-links { display: flex; gap: 4px; margin-left: auto; }
.nav-links a {
  padding: 8px 15px; border-radius: var(--r-full); font-size: 14.5px; font-weight: 600;
  color: var(--ink-2); transition: background .2s, color .2s;
}
.nav-links a:hover { background: var(--white); color: var(--wood); }
.nav-actions { display: flex; gap: 10px; align-items: center; }
.nav-toggle { display: none; width: 42px; height: 42px; border-radius: 12px; background: var(--white); border: 1px solid var(--line); flex-direction: column; gap: 4px; align-items: center; justify-content: center; }
.nav-toggle span { display: block; width: 18px; height: 2px; border-radius: 2px; background: var(--wood); transition: transform .25s, opacity .2s; }
.nav.is-open .nav-toggle span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.nav.is-open .nav-toggle span:nth-child(2) { opacity: 0; }
.nav.is-open .nav-toggle span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* 移动端折叠菜单容器：桌面端视作透明（子元素直接参与 .nav 布局） */
.nav-collapse { display: contents; }

/* ---------------- Hero ---------------- */
.hero { position: relative; padding: 148px 0 72px; overflow: hidden; }
.hero-bg { position: absolute; inset: 0; pointer-events: none; overflow: hidden; }
.hero-blob {
  position: absolute; border-radius: 50%; filter: blur(60px); opacity: .55;
}
.hero-blob.b1 { width: 460px; height: 460px; background: #FFD9CD; top: -120px; right: -80px; animation: floatY 9s ease-in-out infinite; }
.hero-blob.b2 { width: 380px; height: 380px; background: #F0E0C8; top: 180px; left: -140px; animation: floatY 11s ease-in-out infinite reverse; }
.hero-blob.b3 { width: 300px; height: 300px; background: #DBF0E6; bottom: -80px; right: 24%; animation: floatY 13s ease-in-out infinite; }
.hero-notes { position: absolute; inset: 0; }
.hero-note { position: absolute; color: var(--wood-pale); font-size: 26px; opacity: .5; animation: floatY 7s ease-in-out infinite; }

.hero-inner { position: relative; display: grid; grid-template-columns: 1.05fr .95fr; gap: 56px; align-items: center; }
.hero-badge {
  display: inline-flex; align-items: center; gap: 9px; background: var(--white);
  padding: 8px 16px 8px 9px; border-radius: var(--r-full); border: 1px solid var(--line);
  box-shadow: var(--shadow-sm); font-size: 13.5px; font-weight: 600; color: var(--ink-2);
}
.hero-badge b { background: var(--coral); color: #fff; padding: 3px 10px; border-radius: var(--r-full); font-size: 12px; }
.hero h1 {
  font-size: clamp(36px, 5vw, 60px); margin: 22px 0 20px; color: var(--wood-deep);
  letter-spacing: -.03em; line-height: 1.14;
}
.hero h1 em {
  font-style: normal; position: relative; color: var(--coral); white-space: nowrap;
}
.hero h1 em::after {
  content: ""; position: absolute; left: 0; right: 0; bottom: 6px; height: 12px;
  background: var(--coral-soft); border-radius: 99px; z-index: -1;
}
.hero-desc { font-size: 17px; color: var(--ink-2); max-width: 500px; margin-bottom: 30px; }
.hero-cta { display: flex; gap: 12px; flex-wrap: wrap; }
.hero-stats { display: flex; gap: 34px; margin-top: 40px; padding-top: 28px; border-top: 1px dashed var(--line-2); }
.hero-stats b { display: block; font-family: var(--font-num); font-size: 30px; color: var(--wood); line-height: 1; }
.hero-stats span { font-size: 13px; color: var(--ink-3); }

/* Hero 右侧插画卡 */
.hero-visual { position: relative; }
.hero-card {
  background: var(--white); border-radius: var(--r-xl); padding: 26px;
  box-shadow: var(--shadow-lg); border: 1px solid var(--line);
  transform: rotate(-1.6deg);
}
.hero-card-top { display: flex; align-items: center; gap: 12px; margin-bottom: 18px; }
.hero-avatar {
  width: 46px; height: 46px; border-radius: 14px; display: grid; place-items: center;
  background: linear-gradient(140deg, #FFC9B6, var(--coral)); color: #fff; font-weight: 800; font-size: 17px;
}
.hero-card-top div b { display: block; font-size: 15px; color: var(--wood-deep); }
.hero-card-top div span { font-size: 12.5px; color: var(--ink-3); }
.mini-staff { background: var(--cream); border-radius: var(--r); padding: 14px 12px; margin-bottom: 16px; }
.hero-progress { display: grid; gap: 13px; }
.hp-row { display: grid; gap: 6px; }
.hp-row .hp-label { display: flex; justify-content: space-between; font-size: 13px; color: var(--ink-2); font-weight: 600; }
.hero-float {
  position: absolute; background: var(--white); border-radius: var(--r);
  padding: 11px 15px; box-shadow: var(--shadow); border: 1px solid var(--line);
  display: flex; align-items: center; gap: 10px; font-size: 13px; font-weight: 700; color: var(--wood-deep);
}
.hero-float i { font-style: normal; font-size: 18px; }
.hero-float.f1 { top: -18px; left: -22px; animation: floatY 6s ease-in-out infinite; }
.hero-float.f2 { bottom: 34px; right: -26px; animation: floatY 8s ease-in-out infinite 1s; }

/* ---------------- 琴键区 ---------------- */
.piano-stage {
  position: relative; border-radius: var(--r-xl); padding: 26px 26px 30px;
  background: linear-gradient(165deg, #4A3020 0%, #35211410 0%, #402A1B 40%, #2E1D12 100%);
  background: linear-gradient(165deg, #503523 0%, #3E2718 55%, #2C1B10 100%);
  box-shadow: 0 30px 70px rgba(62,41,25,.34), inset 0 1px 0 rgba(255,255,255,.08);
  overflow: hidden;
}
.piano-stage::before {
  content: ""; position: absolute; inset: 0;
  background: repeating-linear-gradient(96deg, rgba(255,255,255,.03) 0 2px, transparent 2px 9px);
  pointer-events: none;
}
.piano-toolbar {
  position: relative; display: flex; flex-wrap: wrap; gap: 10px; align-items: center;
  margin-bottom: 18px;
}
.pt-group { display: flex; background: rgba(255,255,255,.08); border-radius: var(--r-full); padding: 4px; gap: 2px; }
.pt-btn {
  padding: 7px 15px; border-radius: var(--r-full); font-size: 13px; font-weight: 700;
  color: #E8D9C7; transition: background .2s, color .2s;
}
.pt-btn.is-on { background: var(--coral); color: #fff; box-shadow: 0 4px 12px rgba(255,122,89,.4); }
.pt-btn:hover:not(.is-on) { background: rgba(255,255,255,.1); }
.pt-label { color: #B9A48D; font-size: 12.5px; font-weight: 700; letter-spacing: .04em; margin-right: 2px; }
.pt-select {
  background: rgba(255,255,255,.08); border: 1px solid rgba(255,255,255,.14); color: #F0E4D5;
  border-radius: var(--r-full); padding: 8px 14px; font-size: 13px; font-weight: 600; outline: none;
}
.pt-select option { color: var(--ink); }
.pt-spacer { margin-left: auto; }

/* 跟弹提示条 */
.song-hint {
  position: relative; display: none; align-items: center; gap: 14px;
  background: rgba(255,255,255,.07); border: 1px solid rgba(255,255,255,.12);
  border-radius: var(--r); padding: 12px 16px; margin-bottom: 16px;
}
.song-hint.is-on { display: flex; }
.song-next { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.song-chip {
  min-width: 34px; height: 34px; padding: 0 10px; border-radius: 10px; display: grid; place-items: center;
  background: rgba(255,255,255,.1); color: #D9C7B2; font-weight: 800; font-size: 14px; transition: all .25s;
}
.song-chip.is-now { background: var(--coral); color: #fff; transform: scale(1.12); box-shadow: 0 6px 16px rgba(255,122,89,.45); }
.song-chip.is-done { background: rgba(95,184,148,.24); color: #9EDCC1; }
.song-meta { margin-left: auto; color: #C9B49C; font-size: 13px; font-weight: 700; }

/* 键盘本体 */
.keyboard-wrap { position: relative; }
.note-particles { position: absolute; left: 0; right: 0; bottom: 100%; height: 130px; pointer-events: none; overflow: hidden; }
.particle {
  position: absolute; bottom: 0; font-size: 22px; font-weight: 800;
  animation: riseFade 1.5s cubic-bezier(.2,.7,.3,1) forwards; text-shadow: 0 4px 14px rgba(0,0,0,.35);
}
.keyboard {
  position: relative; display: flex; height: 210px; user-select: none;
  border-radius: 0 0 14px 14px; overflow: hidden;
  box-shadow: 0 -3px 0 #24150C, 0 18px 34px rgba(0,0,0,.36);
}
.key-white {
  position: relative; flex: 1 1 0; min-width: 0;
  background: linear-gradient(180deg, #FFFDFA 0%, #F6F0E7 78%, #E5DACB 100%);
  border-right: 1px solid #D8CBB9;
  border-radius: 0 0 9px 9px;
  display: flex; align-items: flex-end; justify-content: center; padding-bottom: 12px;
  transition: background .08s, transform .06s;
  cursor: pointer;
}
.key-white:last-child { border-right: none; }
.key-white .kb-label { font-size: 12px; font-weight: 800; color: var(--ink-4); pointer-events: none; }
.key-white .kb-key { position: absolute; bottom: 32px; font-size: 10px; color: #CBBBA8; font-weight: 700; pointer-events: none; }
.key-white.is-down {
  background: linear-gradient(180deg, #FFE7DE 0%, #FFC9B7 100%);
  transform: translateY(3px);
  box-shadow: inset 0 3px 8px rgba(232,95,61,.28);
}
.key-white.is-down .kb-label { color: var(--coral-dark); }
.key-white.is-target { background: linear-gradient(180deg, #EAFBF3 0%, #BFEBD8 100%); }
.key-white.is-target::after {
  content: ""; position: absolute; top: 14px; left: 50%; transform: translateX(-50%);
  width: 9px; height: 9px; border-radius: 50%; background: var(--mint);
  box-shadow: 0 0 0 0 rgba(95,184,148,.6); animation: pulseDot 1.2s infinite;
}
@keyframes pulseDot { 0% { box-shadow: 0 0 0 0 rgba(95,184,148,.65); } 100% { box-shadow: 0 0 0 14px rgba(95,184,148,0); } }

.key-black {
  position: absolute; top: 0; z-index: 3; height: 62%;
  background: linear-gradient(180deg, #4A4038 0%, #23191300 0%, #2B211A 62%, #14100C 100%);
  background: linear-gradient(180deg, #4F433A 0%, #2A211A 70%, #15100B 100%);
  border-radius: 0 0 7px 7px;
  box-shadow: 0 5px 10px rgba(0,0,0,.5), inset 0 -3px 0 rgba(255,255,255,.06);
  display: flex; align-items: flex-end; justify-content: center; padding-bottom: 9px;
  cursor: pointer; transition: transform .06s, background .08s;
}
.key-black .kb-label { font-size: 10px; font-weight: 800; color: #8C7C6C; pointer-events: none; }
.key-black.is-down {
  background: linear-gradient(180deg, #FF9C7E 0%, #D8532F 100%);
  transform: translateY(3px);
}
.key-black.is-down .kb-label { color: #fff; }
.key-black.is-target { background: linear-gradient(180deg, #5FB894 0%, #2F7D5F 100%); }

.piano-tip { position: relative; margin-top: 16px; color: #B9A48D; font-size: 13px; display: flex; gap: 18px; flex-wrap: wrap; }
.piano-tip b { color: #EBDCC9; }
.kbd {
  display: inline-block; min-width: 20px; text-align: center; padding: 2px 6px;
  background: rgba(255,255,255,.12); border: 1px solid rgba(255,255,255,.16);
  border-radius: 6px; font-size: 11.5px; font-weight: 700; color: #F0E4D5; margin: 0 2px;
}

/* ---------------- 学习区 ---------------- */
.learn-grid { display: grid; grid-template-columns: 1.15fr .85fr; gap: 24px; align-items: start; }

.learn-panel { padding: 26px; }
.learn-tabs { display: flex; gap: 6px; background: var(--cream-2); padding: 5px; border-radius: var(--r-full); margin-bottom: 24px; }
.learn-tab {
  flex: 1; padding: 10px 8px; border-radius: var(--r-full); font-size: 14px; font-weight: 700;
  color: var(--ink-2); transition: all .22s;
}
.learn-tab.is-on { background: var(--white); color: var(--wood); box-shadow: var(--shadow-sm); }

.staff-box { background: var(--cream); border-radius: var(--r-lg); padding: 20px 10px; margin-bottom: 20px; position: relative; }
.staff-box.is-right { box-shadow: inset 0 0 0 2px var(--mint); }
.staff-box.is-wrong { box-shadow: inset 0 0 0 2px var(--coral); animation: shakeX .4s; }
@keyframes shakeX { 0%,100%{transform:translateX(0)} 25%{transform:translateX(-7px)} 75%{transform:translateX(7px)} }

.opt-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; }
.opt {
  padding: 15px 6px; border-radius: var(--r); background: var(--cream-2);
  font-weight: 800; font-size: 17px; color: var(--wood-dark); text-align: center;
  border: 2px solid transparent; transition: all .18s;
}
.opt small { display: block; font-size: 11px; font-weight: 600; color: var(--ink-3); margin-top: 2px; }
.opt:hover { background: var(--cream-3); transform: translateY(-2px); }
.opt.is-right { background: var(--mint-soft); border-color: var(--mint); color: #2F7D5F; }
.opt.is-wrong { background: var(--coral-soft); border-color: var(--coral); color: var(--coral-dark); }

.quiz-bar { display: flex; align-items: center; gap: 16px; margin-bottom: 18px; }
.quiz-score { display: flex; gap: 18px; }
.quiz-score div b { font-family: var(--font-num); font-size: 22px; color: var(--wood); display: block; line-height: 1; }
.quiz-score div span { font-size: 11.5px; color: var(--ink-3); }
.quiz-feedback { margin-top: 16px; min-height: 24px; font-weight: 700; font-size: 14px; }
.quiz-feedback.ok { color: var(--mint); }
.quiz-feedback.no { color: var(--coral-dark); }

.ear-play {
  width: 92px; height: 92px; border-radius: 50%; margin: 0 auto 18px; display: grid; place-items: center;
  background: linear-gradient(140deg, #FFB49A, var(--coral)); color: #fff; font-size: 32px;
  box-shadow: var(--shadow-coral); position: relative; transition: transform .2s;
}
.ear-play:hover { transform: scale(1.06); }
.ear-play::after {
  content: ""; position: absolute; inset: 0; border-radius: 50%; border: 2px solid var(--coral);
  animation: pulseRing 2s infinite;
}

.scale-list { display: grid; gap: 10px; }
.scale-item {
  display: flex; align-items: center; gap: 14px; padding: 13px 16px;
  background: var(--cream-2); border-radius: var(--r); transition: all .18s; text-align: left;
}
.scale-item:hover { background: var(--cream-3); transform: translateX(4px); }
.scale-item .si-play {
  width: 36px; height: 36px; border-radius: 50%; flex: none; display: grid; place-items: center;
  background: var(--white); color: var(--wood); box-shadow: var(--shadow-sm); font-size: 14px;
}
.scale-item b { display: block; font-size: 14.5px; color: var(--wood-deep); }
.scale-item span { font-size: 12.5px; color: var(--ink-3); }

/* 侧栏：音符字典 */
.note-dict { padding: 24px; }
.dict-row { display: flex; align-items: center; gap: 13px; padding: 11px 0; border-bottom: 1px dashed var(--line); }
.dict-row:last-child { border-bottom: none; }
.dict-glyph {
  width: 44px; height: 44px; border-radius: 13px; flex: none; display: grid; place-items: center;
  background: var(--cream-2); font-size: 22px; color: var(--wood);
}
.dict-row b { display: block; font-size: 14.5px; color: var(--wood-deep); }
.dict-row span { font-size: 12.5px; color: var(--ink-3); }
.dict-row .dict-beat { margin-left: auto; font-family: var(--font-num); font-weight: 800; color: var(--coral); font-size: 15px; }

.metro-card { padding: 22px; margin-top: 20px; }
.metro-top { display: flex; align-items: baseline; gap: 8px; margin-bottom: 6px; }
.metro-bpm { font-family: var(--font-num); font-size: 40px; font-weight: 800; color: var(--wood-deep); line-height: 1; }
.metro-dots { display: flex; gap: 8px; margin: 16px 0; }
.metro-dot { width: 13px; height: 13px; border-radius: 50%; background: var(--cream-3); transition: all .1s; }
.metro-dot.is-on { background: var(--coral); transform: scale(1.35); }
.metro-dot.is-on.is-first { background: var(--wood); }
input[type=range].slider {
  -webkit-appearance: none; width: 100%; height: 6px; border-radius: 99px;
  background: var(--cream-3); outline: none;
}
input[type=range].slider::-webkit-slider-thumb {
  -webkit-appearance: none; width: 20px; height: 20px; border-radius: 50%;
  background: var(--white); border: 3px solid var(--coral); cursor: pointer;
  box-shadow: var(--shadow-sm);
}

/* ---------------- 成果与评价 ---------------- */
.stat-strip { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; margin-bottom: 46px; }
.stat-card { padding: 26px 22px; text-align: center; position: relative; overflow: hidden; }
.stat-card::before {
  content: ""; position: absolute; top: -30px; right: -30px; width: 96px; height: 96px;
  border-radius: 50%; opacity: .5;
}
.stat-card:nth-child(1)::before { background: var(--coral-soft); }
.stat-card:nth-child(2)::before { background: var(--mint-soft); }
.stat-card:nth-child(3)::before { background: var(--gold-soft); }
.stat-card:nth-child(4)::before { background: var(--sky-soft); }
.stat-card b { position: relative; font-family: var(--font-num); font-size: 42px; color: var(--wood-deep); line-height: 1; display: block; }
.stat-card b i { font-style: normal; font-size: 20px; color: var(--coral); }
.stat-card span { position: relative; font-size: 14px; color: var(--ink-2); font-weight: 600; }

.video-wall { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; margin-bottom: 46px; }
.video-card {
  border-radius: var(--r-lg); overflow: hidden; position: relative; aspect-ratio: 3/4;
  box-shadow: var(--shadow); cursor: pointer; transition: transform .3s cubic-bezier(.22,1,.36,1), box-shadow .3s;
}
.video-card:hover { transform: translateY(-8px) scale(1.02); box-shadow: var(--shadow-lg); }
.vc-cover { position: absolute; inset: 0; }
.vc-cover::after {
  content: ""; position: absolute; inset: 0;
  background: linear-gradient(180deg, rgba(0,0,0,0) 35%, rgba(46,29,18,.82) 100%);
}
.vc-keys { position: absolute; left: 0; right: 0; bottom: 34%; height: 54px; display: flex; opacity: .35; }
.vc-keys i { flex: 1; background: rgba(255,255,255,.75); margin-right: 2px; border-radius: 0 0 4px 4px; }
.vc-play {
  position: absolute; top: 50%; left: 50%; transform: translate(-50%,-60%);
  width: 54px; height: 54px; border-radius: 50%; background: rgba(255,255,255,.92);
  display: grid; place-items: center; color: var(--coral); font-size: 18px; z-index: 2;
  box-shadow: 0 8px 20px rgba(0,0,0,.25); transition: transform .25s;
}
.video-card:hover .vc-play { transform: translate(-50%,-60%) scale(1.12); }
.vc-info { position: absolute; left: 16px; right: 16px; bottom: 14px; z-index: 2; color: #fff; }
.vc-info b { display: block; font-size: 15px; }
.vc-info span { font-size: 12.5px; opacity: .8; }
.vc-badge {
  position: absolute; top: 12px; left: 12px; z-index: 2;
  background: rgba(255,255,255,.92); color: var(--wood-dark);
  padding: 4px 10px; border-radius: var(--r-full); font-size: 11.5px; font-weight: 800;
}

.review-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.review-card { padding: 26px 24px; position: relative; }
.review-card .quote { position: absolute; top: 16px; right: 22px; font-size: 54px; color: var(--cream-3); font-family: Georgia, serif; line-height: 1; }
.review-stars { color: var(--gold); font-size: 14px; letter-spacing: 2px; margin-bottom: 12px; }
.review-text { font-size: 14.5px; color: var(--ink-2); line-height: 1.85; margin-bottom: 18px; position: relative; }
.review-who { display: flex; align-items: center; gap: 11px; padding-top: 16px; border-top: 1px dashed var(--line); }
.review-avatar { width: 40px; height: 40px; border-radius: 12px; display: grid; place-items: center; color: #fff; font-weight: 800; font-size: 15px; }
.review-who b { display: block; font-size: 14px; color: var(--wood-deep); }
.review-who span { font-size: 12px; color: var(--ink-3); }

/* ---------------- Footer ---------------- */
.site-footer { background: var(--wood-deep); color: #E4D5C4; padding: 62px 0 26px; margin-top: 20px; }
.footer-grid { display: grid; grid-template-columns: 1.5fr 1fr 1fr 1.2fr; gap: 40px; }
.footer-grid h4 { color: #fff; font-size: 15px; margin-bottom: 16px; }
.footer-about p { font-size: 13.5px; color: #B49E89; max-width: 300px; margin-top: 14px; line-height: 1.8; }
.footer-links { display: grid; gap: 10px; }
.footer-links a { font-size: 13.5px; color: #C9B49C; transition: color .2s; }
.footer-links a:hover { color: var(--coral-soft); }
.footer-contact div { font-size: 13.5px; color: #C9B49C; margin-bottom: 10px; display: flex; gap: 9px; }
.footer-qr {
  width: 104px; height: 104px; border-radius: 14px; background: rgba(255,255,255,.08);
  display: grid; place-items: center; color: #8C7663; font-size: 12px; text-align: center;
  border: 1px dashed rgba(255,255,255,.18); margin-top: 12px; padding: 6px; overflow: hidden;
}
.footer-qr img {
  width: 100%; height: 100%; object-fit: cover; border-radius: 9px; background: #fff;
  box-shadow: 0 4px 14px rgba(0,0,0,.25);
}
.footer-bottom {
  margin-top: 42px; padding-top: 22px; border-top: 1px solid rgba(255,255,255,.1);
  display: flex; justify-content: space-between; flex-wrap: wrap; gap: 10px;
  font-size: 12.5px; color: #8C7663;
}
.footer-logo { display: flex; align-items: center; gap: 11px; font-weight: 900; font-size: 18px; color: #fff; }

/* ---------------- Toast ---------------- */
.toast-wrap { position: fixed; bottom: 28px; left: 50%; transform: translateX(-50%); z-index: 300; display: grid; gap: 10px; }
.toast {
  background: var(--wood-deep); color: #fff; padding: 12px 22px; border-radius: var(--r-full);
  font-size: 14px; font-weight: 600; box-shadow: var(--shadow-lg); animation: popIn .25s;
}

/* ---------------- 响应式 ---------------- */
@media (max-width: 1024px) {
  .hero-inner { grid-template-columns: 1fr; }
  .hero-visual { max-width: 460px; }
  .learn-grid { grid-template-columns: 1fr; }
  .stat-strip { grid-template-columns: repeat(2, 1fr); }
  .video-wall { grid-template-columns: repeat(2, 1fr); }
  .review-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
/* 平板 / 手机：导航折叠为汉堡菜单 */
@media (max-width: 860px) {
  .nav { flex-wrap: wrap; }
  .nav-toggle { display: flex; margin-left: auto; }
  .nav-collapse {
    display: none; order: 3; width: 100%; flex-direction: column; gap: 12px;
    margin-top: 12px; padding: 16px; border-radius: 18px;
    background: rgba(253, 248, 241, .97); backdrop-filter: blur(14px);
    border: 1px solid var(--line); box-shadow: var(--shadow);
  }
  .nav.is-open .nav-collapse { display: flex; }
  .nav-links { flex-direction: column; gap: 4px; margin-left: 0; width: 100%; }
  .nav-links a { padding: 12px 14px; background: var(--white); }
  .nav-actions { flex-direction: column; width: 100%; gap: 10px; }
  .nav-actions .btn { width: 100%; }
  .site-header:has(.nav.is-open) { background: rgba(253, 248, 241, .97); backdrop-filter: blur(14px); box-shadow: 0 1px 0 var(--line); padding: 10px 0; }
}
@media (max-width: 720px) {
  .container { width: calc(100% - 32px); }
  .section { padding: 64px 0; }
  .keyboard { height: 160px; }
  .opt-grid { grid-template-columns: repeat(2, 1fr); }
  .stat-strip { grid-template-columns: repeat(2, 1fr); }
  .video-wall { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr; }
  .hero-float { display: none; }
  .piano-stage { padding: 16px 12px 20px; }
}
/* 小屏手机细调 */
@media (max-width: 480px) {
  .container { width: calc(100% - 24px); }
  .section { padding: 52px 0; }
  .hero { padding: 120px 0 54px; }
  .hero h1 { font-size: clamp(30px, 9vw, 40px); }
  .hero-stats { gap: 16px 22px; flex-wrap: wrap; }
  .hero-stats > div { flex: 1 1 40%; }
  .keyboard { height: 138px; }
  .key-white .kb-label { font-size: 10px; }
  .key-white .kb-key { bottom: 24px; font-size: 9px; }
  .stat-strip { grid-template-columns: 1fr 1fr; gap: 12px; }
  .stat-card { padding: 20px 14px; }
  .stat-card b { font-size: 34px; }
  .video-wall { grid-template-columns: 1fr 1fr; gap: 12px; }
  .piano-toolbar { gap: 8px; }
  .piano-tip { gap: 10px; font-size: 12px; }
  .opt-grid { gap: 8px; }
  .footer-about p { max-width: none; }
}