/* 书笙乐谱（SSScore）官网样式 —— 墨绿 / 宣纸 / 朱砂，纯静态无依赖 */

@font-face {
  font-family: "Shusheng Serif CJK";
  src: url("../fonts/shusheng-serif-cjk.woff2") format("woff2");
  font-weight: 400 700;
  font-display: swap;
}
@font-face {
  font-family: "Shusheng Sans CJK";
  src: url("../fonts/shusheng-sans-cjk.woff2") format("woff2");
  font-weight: 400 700;
  font-display: swap;
}

:root {
  --deep: #0b1a12;
  --deep-2: #102a1c;
  --deep-3: #163423;
  --paper: #f3eee3;
  --paper-2: #fbf8f1;
  --card: #fffdf7;
  --ink: #16241b;
  --muted: #5e6c60;
  --line: rgba(22, 36, 27, .12);
  --cinnabar: #b23a2b;
  --cinnabar-2: #cb4a39;
  --jade: #7fa86e;
  --gold: #c8a96a;
  --on-deep: #e9efe6;
  --on-deep-muted: #9db0a0;
  --serif: "Shusheng Serif CJK", "Noto Serif SC", "Songti SC", "SimSun", serif;
  --sans: "Shusheng Sans CJK", system-ui, -apple-system, "Segoe UI", "Microsoft YaHei UI", "Microsoft YaHei", "PingFang SC", "Hiragino Sans GB", sans-serif;
  --shadow-card: 0 24px 60px -28px rgba(6, 18, 10, .45), 0 2px 0 rgba(255, 255, 255, .6) inset;
  --radius: 18px;
  --shell: 1180px;
}

*, *::before, *::after { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 88px; }

body {
  margin: 0;
  background: var(--deep);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { max-width: 100%; height: auto; display: block; }
a { color: inherit; }
h1, h2, h3, h4 { font-family: var(--serif); font-weight: 700; margin: 0; line-height: 1.28; }
p { margin: 0; }
ul, ol, dl, dd { margin: 0; padding: 0; }
li { list-style: none; }

.shell { width: min(var(--shell), calc(100% - 48px)); margin-inline: auto; }
.shell.narrow { width: min(880px, calc(100% - 48px)); }
.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}
.skip-link {
  position: absolute; left: 16px; top: -60px; z-index: 100;
  background: var(--card); color: var(--ink); padding: 10px 18px;
  border-radius: 10px; text-decoration: none; transition: top .18s ease;
}
.skip-link:focus { top: 12px; }

:focus-visible { outline: 2px solid var(--jade); outline-offset: 3px; }

/* ---------- 按钮 ---------- */
.btn {
  --btn-fg: var(--on-deep);
  display: inline-flex; align-items: center; gap: 10px;
  padding: 14px 26px; border-radius: 999px;
  font-size: 16px; font-weight: 600; text-decoration: none;
  border: 1px solid transparent; cursor: pointer;
  transition: transform .18s ease, box-shadow .18s ease, background .18s ease, border-color .18s ease, color .18s ease;
}
.btn svg { width: 16px; height: 16px; }
.btn-primary {
  background: linear-gradient(180deg, var(--cinnabar-2), var(--cinnabar));
  color: #fff;
  box-shadow: 0 1px 0 rgba(255, 255, 255, .3) inset, 0 -2px 0 rgba(90, 24, 14, .35) inset,
              0 16px 32px -16px rgba(178, 58, 43, .9);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 1px 0 rgba(255, 255, 255, .34) inset, 0 -2px 0 rgba(90, 24, 14, .3) inset, 0 22px 38px -16px rgba(178, 58, 43, 1); }
.btn-ghost { border-color: rgba(233, 239, 230, .28); color: var(--on-deep); background: rgba(255, 255, 255, .04); }
.btn-ghost:hover { border-color: rgba(233, 239, 230, .6); background: rgba(255, 255, 255, .09); }
.section-paper .btn-ghost { border-color: rgba(22, 36, 27, .22); color: var(--ink); background: rgba(22, 36, 27, .04); }
.section-paper .btn-ghost:hover { background: rgba(22, 36, 27, .09); }
.btn-sm { padding: 9px 18px; font-size: 14.5px; }
.btn-lg { padding: 17px 32px; font-size: 17px; }

/* ---------- 头部 ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(11, 26, 18, .82);
  backdrop-filter: blur(14px) saturate(140%);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  border-bottom: 1px solid rgba(233, 239, 230, .08);
  transition: background .25s ease, border-color .25s ease;
}
.site-header.is-scrolled { background: rgba(8, 20, 14, .95); border-bottom-color: rgba(233, 239, 230, .16); }
.header-inner { display: flex; align-items: center; gap: 24px; height: 72px; }
.brand { display: inline-flex; align-items: center; gap: 12px; text-decoration: none; color: var(--on-deep); }
.brand-mark { width: 38px; height: 38px; }
.brand-text { display: flex; flex-direction: column; line-height: 1.1; }
.brand-zh { font-family: var(--serif); font-size: 20px; font-weight: 700; letter-spacing: .06em; }
.brand-en { font-size: 11.5px; letter-spacing: .28em; text-transform: uppercase; color: var(--on-deep-muted); }
.site-nav { display: flex; align-items: center; gap: 4px; margin-left: auto; }
.site-nav a {
  color: var(--on-deep-muted); text-decoration: none; font-size: 15px;
  padding: 9px 13px; border-radius: 999px; transition: color .18s ease, background .18s ease;
}
.site-nav a:hover { color: var(--on-deep); background: rgba(255, 255, 255, .07); }
.site-nav a.is-current { color: var(--on-deep); }
.site-nav .nav-cta { margin-left: 12px; color: #fff; }
.site-nav .nav-cta:hover { background: linear-gradient(180deg, var(--cinnabar-2), var(--cinnabar)); }
.nav-toggle {
  display: none; margin-left: auto; width: 44px; height: 44px; border-radius: 12px;
  border: 1px solid rgba(233, 239, 230, .2); background: rgba(255, 255, 255, .05);
  cursor: pointer; position: relative;
}
.nav-toggle-bar, .nav-toggle-bar::before, .nav-toggle-bar::after {
  content: ""; position: absolute; left: 12px; width: 20px; height: 1.6px;
  background: var(--on-deep); transition: transform .22s ease, opacity .22s ease;
}
.nav-toggle-bar { top: 21px; }
.nav-toggle-bar::before { left: 0; top: -6px; }
.nav-toggle-bar::after { left: 0; top: 6px; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar { transform: rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar::before { opacity: 0; }
.nav-toggle[aria-expanded="true"] .nav-toggle-bar::after { transform: rotate(-90deg); top: 0; }

/* ---------- 首屏 ---------- */
.hero { position: relative; overflow: hidden; color: var(--on-deep); padding: 84px 0 0; }
.hero-bg { position: absolute; inset: 0; pointer-events: none; }
.hero-staff {
  position: absolute; inset: 0;
  background-image: repeating-linear-gradient(to bottom, rgba(255, 255, 255, .055) 0 1px, transparent 1px 46px);
  mask-image: linear-gradient(to bottom, transparent, #000 18%, #000 72%, transparent);
  -webkit-mask-image: linear-gradient(to bottom, transparent, #000 18%, #000 72%, transparent);
}
.hero-glow {
  position: absolute; width: 900px; height: 900px; right: -220px; top: -260px;
  background: radial-gradient(circle, rgba(127, 168, 110, .3), transparent 62%);
  filter: blur(30px);
}
.hero-numbers {
  position: absolute; right: 3%; bottom: 4%;
  font-family: var(--serif); font-size: clamp(140px, 22vw, 320px); line-height: .8;
  color: rgba(255, 255, 255, .045); letter-spacing: .04em; user-select: none;
}
.hero-inner {
  position: relative; display: grid; grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
  gap: 56px; align-items: center; padding-bottom: 76px;
}
.pill {
  display: inline-flex; align-items: center; gap: 9px;
  padding: 7px 16px 7px 13px; border-radius: 999px;
  background: rgba(127, 168, 110, .14); border: 1px solid rgba(127, 168, 110, .34);
  color: #cfe0c6; font-size: 13.5px; letter-spacing: .04em;
}
.pill-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--jade); box-shadow: 0 0 0 4px rgba(127, 168, 110, .22); }
.hero h1 {
  font-size: clamp(40px, 5.4vw, 66px); letter-spacing: .02em; margin: 22px 0 0;
}
.hero h1 em {
  font-style: normal; position: relative; display: inline-block; padding-bottom: 6px;
}
.hero h1 em::after {
  content: ""; position: absolute; left: 2px; right: 6px; bottom: 0; height: 5px; border-radius: 3px;
  background: linear-gradient(90deg, var(--cinnabar), rgba(200, 169, 106, .85));
  transform: scaleX(0); transform-origin: left; animation: sweep 1s .35s cubic-bezier(.2, .8, .2, 1) forwards;
}
@keyframes sweep { to { transform: scaleX(1); } }
.lead { color: #c6d3c0; font-size: 18.5px; margin-top: 22px; max-width: 34em; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 34px; }
.hero-meta { display: flex; flex-wrap: wrap; gap: 8px 18px; margin-top: 30px; color: var(--on-deep-muted); font-size: 14px; }
.hero-meta li { display: inline-flex; align-items: center; gap: 8px; }
.hero-meta li::before { content: ""; width: 4px; height: 4px; border-radius: 50%; background: var(--gold); }

/* 首屏下载：一排平台胶囊 + 一个大下载按钮，默认选中来访设备那一档（由 main.js 决定选中谁） */
.hero-dl { margin-top: 32px; }
.hero-dl-tabs {
  display: inline-flex; flex-wrap: wrap; gap: 4px; padding: 5px; border-radius: 999px;
  background: rgba(255, 255, 255, .06); border: 1px solid rgba(233, 239, 230, .14);
}
.hero-dl-tab {
  appearance: none; cursor: pointer; font: inherit; font-size: 14.5px;
  border: 0; background: transparent; color: var(--on-deep-muted);
  padding: 7px 16px; border-radius: 999px;
  transition: color .18s ease, background .18s ease, box-shadow .18s ease;
}
.hero-dl-tab:hover { color: var(--on-deep); }
.hero-dl-tab.is-active {
  color: #f4ecd8; background: rgba(200, 169, 106, .2);
  box-shadow: 0 0 0 1px rgba(200, 169, 106, .5) inset;
}
.hero-dl-line { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 18px; margin-top: 18px; }
.hero-dl-size { font-style: normal; font-size: 14px; font-weight: 600; opacity: .85; }
.hero-dl-meta { font-size: 14px; color: var(--on-deep-muted); }

.hero-visual { position: relative; padding-top: 8px; }

/* 层叠的三种谱式：后面两张斜着探出来，前面那张完整可读 */
.sheet-stack { position: relative; height: 336px; }
.sheet {
  position: absolute; margin: 0; background: linear-gradient(180deg, #fffef9, #f6f1e6);
  border: 1px solid rgba(22, 36, 27, .1); border-radius: 16px; padding: 14px 16px 12px;
  color: var(--ink); box-shadow: 0 30px 60px -30px rgba(3, 12, 7, .85), 0 4px 14px -8px rgba(3, 12, 7, .6);
  transition: transform .5s cubic-bezier(.2, .8, .2, 1), box-shadow .5s ease;
}
.sheet-cap { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 8px; }
.sheet-label {
  font-family: var(--serif); font-size: 15px; font-weight: 700; letter-spacing: .04em;
  padding: 3px 12px; border-radius: 999px; background: var(--deep-2); color: var(--paper);
}
.sheet-tag { font-size: 12px; color: #8b9488; letter-spacing: .02em; }
.sheet img { width: 100%; }
.sheet-back-a { width: 60%; left: -6%; top: 0; transform: rotate(-5deg); z-index: 1; opacity: .96; }
.sheet-back-b { width: 58%; right: -7%; top: -10px; transform: rotate(4.5deg); z-index: 2; opacity: .96; }
.sheet-front { width: 82%; left: 9%; bottom: 0; z-index: 3; }
.hero-visual:hover .sheet-back-a { transform: rotate(-7deg) translate(-10px, -8px); }
.hero-visual:hover .sheet-back-b { transform: rotate(6.5deg) translate(10px, -8px); }
.stack-note {
  position: relative; z-index: 4; margin-top: 26px; text-align: center;
  font-size: 13.5px; color: var(--on-deep-muted); letter-spacing: .02em;
}

.stats {
  position: relative; display: grid; grid-template-columns: repeat(4, 1fr);
  border-bottom: 1px solid rgba(200, 169, 106, .3);
  border-top: 1px solid rgba(233, 239, 230, .12);
}
.stat { padding: 26px 8px 30px; border-right: 1px solid rgba(233, 239, 230, .1); }
.stat:last-child { border-right: 0; }
.stat dt { font-size: 14px; color: var(--on-deep-muted); letter-spacing: .06em; }
.stat dd { font-family: var(--serif); font-size: 46px; font-weight: 700; color: var(--on-deep); margin-top: 4px; line-height: 1; text-shadow: 0 12px 26px rgba(0, 0, 0, .45); }
.stat-unit { font-size: 16px; margin-left: 6px; color: var(--on-deep-muted); font-family: var(--sans); font-weight: 400; }

/* ---------- 通用区块 ---------- */
.section { padding: 96px 0; position: relative; }
.section-paper {
  background:
    radial-gradient(1100px 420px at 12% -6%, rgba(200, 169, 106, .13), transparent 62%),
    radial-gradient(900px 380px at 102% 4%, rgba(127, 168, 110, .13), transparent 60%),
    var(--paper);
}
.section-paper::before {
  content: ""; position: absolute; inset: 0 0 auto; height: 120px; pointer-events: none;
  background: linear-gradient(180deg, rgba(22, 36, 27, .07), transparent);
}
.section-deep {
  background:
    radial-gradient(900px 520px at 85% 0%, rgba(127, 168, 110, .16), transparent 62%),
    radial-gradient(700px 420px at 6% 100%, rgba(200, 169, 106, .1), transparent 60%),
    linear-gradient(180deg, var(--deep), var(--deep-2) 55%, var(--deep));
  color: var(--on-deep);
}
.section > .shell { position: relative; z-index: 1; }
.section-head { max-width: 760px; margin-bottom: 46px; }
.section-deep .section-head { color: var(--on-deep); }
.eyebrow {
  display: flex; align-items: center; gap: 12px;
  font-size: 13.5px; letter-spacing: .18em; text-transform: uppercase;
  color: var(--cinnabar); font-weight: 600; margin-bottom: 14px;
}
.eyebrow::before { content: ""; width: 30px; height: 1px; background: currentColor; opacity: .65; }
.section-deep .eyebrow { color: var(--gold); }
.section h2 { font-size: clamp(30px, 3.6vw, 44px); letter-spacing: .01em; }
.section-lead { margin-top: 18px; color: var(--muted); font-size: 18px; max-width: 62ch; }
.section-deep .section-lead { color: #bccbb7; }
.sub-h { font-size: 22px; margin: 54px 0 18px; }
.fine-print { font-size: 14px; color: var(--muted); }
.section-deep .fine-print { color: var(--on-deep-muted); }

.grid-2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 22px; margin-top: 34px; }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 28px 30px;
  box-shadow: 0 1px 0 rgba(255, 255, 255, .95) inset, 0 18px 34px -26px rgba(6, 18, 10, .5),
              0 2px 6px -3px rgba(6, 18, 10, .25);
}
.card h3 { font-size: 21px; margin-bottom: 10px; }
.card p { color: var(--muted); }
.card p + p { margin-top: 12px; }
.card code { font-family: ui-monospace, Consolas, monospace; background: rgba(22, 36, 27, .07); padding: 1px 6px; border-radius: 6px; font-size: .92em; }
.card-accent { border-left: 4px solid var(--cinnabar); }
.contact-line a { color: var(--cinnabar); font-weight: 600; text-decoration: none; border-bottom: 1px solid rgba(178, 58, 43, .35); }
.contact-line a:hover { border-bottom-color: var(--cinnabar); }

/* ---------- 谱式切换 ---------- */
.notation-demo { margin-top: 6px; }
.seg {
  display: inline-flex; gap: 4px; padding: 5px; border-radius: 999px;
  background: rgba(22, 36, 27, .07); border: 1px solid var(--line);
}
.seg-btn {
  appearance: none; border: 0; background: transparent; cursor: pointer;
  font-family: var(--serif); font-size: 16.5px; font-weight: 700; color: #4d5b50;
  padding: 9px 22px; border-radius: 999px; transition: color .18s ease, background .18s ease, box-shadow .18s ease;
}
.seg-btn:hover { color: var(--ink); }
.seg-btn.is-active { background: var(--card); color: var(--cinnabar); box-shadow: 0 6px 18px -10px rgba(6, 18, 10, .5); }
.notation-stage { margin-top: 22px; }
.notation-paper {
  margin: 0; background: linear-gradient(180deg, #fff, #fdfbf6);
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 40px 34px 18px; position: relative; overflow: hidden;
  box-shadow: 0 1px 0 rgba(255, 255, 255, .9) inset, 0 34px 60px -34px rgba(6, 18, 10, .55),
              0 4px 12px -6px rgba(6, 18, 10, .25);
}
.notation-paper::after {
  content: ""; position: absolute; left: 0; right: 0; top: 0; height: 4px;
  background: linear-gradient(90deg, var(--cinnabar), var(--gold), var(--jade));
}
.notation-paper img { width: 100%; transition: opacity .3s ease, transform .3s ease; }
.score-scroll { overflow-x: auto; }
.notation-paper img.is-swapping { opacity: 0; transform: translateY(6px); }
.notation-paper figcaption {
  display: flex; justify-content: space-between; align-items: baseline; gap: 18px;
  margin-top: 22px; padding-top: 14px; border-top: 1px dashed rgba(22, 36, 27, .16);
  font-size: 14.5px; color: var(--muted);
}
.notation-source { color: #94a096; font-size: 13px; white-space: nowrap; }

.notation-list {
  display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 40px;
  border-top: 1px solid var(--line);
}
.notation-list li {
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 15px 4px; border-bottom: 1px solid var(--line);
  font-family: var(--serif); font-size: 18px;
}
.badge {
  font-family: var(--sans); font-size: 12.5px; font-weight: 600; letter-spacing: .04em;
  padding: 4px 12px; border-radius: 999px; white-space: nowrap;
}
.badge-ok { background: rgba(127, 168, 110, .18); color: #38602f; }
.badge-soon { background: rgba(200, 169, 106, .22); color: #805f22; }

/* ---------- AI ---------- */
.ai-flow { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 20px; }
.ai-step {
  position: relative; padding: 28px 26px; border-radius: var(--radius);
  background: linear-gradient(180deg, rgba(255, 255, 255, .085), rgba(255, 255, 255, .03));
  border: 1px solid rgba(233, 239, 230, .14);
  box-shadow: 0 1px 0 rgba(255, 255, 255, .12) inset, 0 24px 44px -30px rgba(0, 0, 0, .8);
  transition: transform .25s ease, background .25s ease, border-color .25s ease, box-shadow .25s ease;
}
.ai-step:hover { transform: translateY(-4px); background: rgba(255, 255, 255, .075); border-color: rgba(200, 169, 106, .35); }
.step-no { font-family: var(--serif); font-size: 15px; letter-spacing: .2em; color: var(--gold); }
.ai-step h3 { font-size: 22px; margin: 10px 0 10px; }
.ai-step p { color: #b9c8b4; font-size: 16px; }

.ai-showcase {
  display: grid; grid-template-columns: minmax(0, .8fr) auto minmax(0, 1.2fr); gap: 22px; align-items: center;
  margin-top: 30px; padding: 30px; border-radius: 22px;
  background: linear-gradient(135deg, rgba(200, 169, 106, .12), rgba(127, 168, 110, .08));
  border: 1px solid rgba(233, 239, 230, .12);
}
.prompt-card { background: var(--card); color: var(--ink); border-radius: 16px; padding: 22px 24px; box-shadow: 0 22px 44px -26px rgba(0, 0, 0, .7); }
.prompt-label { font-size: 12.5px; letter-spacing: .12em; color: #8b9488; }
.prompt-text { font-family: var(--serif); font-size: 25px; font-weight: 700; margin-top: 8px; }
.prompt-opts { font-size: 14px; color: var(--muted); margin-top: 8px; }
.ai-arrow { color: var(--cinnabar-2); }
.ai-arrow svg { width: 64px; height: 24px; }
.result-card { margin: 0; background: #fff; border-radius: 16px; padding: 18px 22px 14px; box-shadow: 0 22px 44px -26px rgba(0, 0, 0, .7); }
.result-card figcaption { display: flex; justify-content: space-between; font-size: 13.5px; color: var(--muted); margin-bottom: 6px; }
.result-tag { color: #94a096; }
.ai-foot { margin-top: 34px; display: flex; flex-wrap: wrap; gap: 22px; align-items: center; justify-content: space-between; }
.ai-foot .hero-actions { margin-top: 0; }

/* ---------- 桌面端 ---------- */
.feature-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 18px; }
.feature {
  background: linear-gradient(180deg, #fffef9, var(--card));
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 26px 26px 24px; position: relative; overflow: hidden;
  box-shadow: 0 1px 0 rgba(255, 255, 255, .95) inset, 0 14px 30px -26px rgba(6, 18, 10, .5);
  transition: transform .25s ease, box-shadow .25s ease;
}
.feature::before {
  content: ""; position: absolute; left: 0; top: 0; bottom: 0; width: 3px;
  background: linear-gradient(180deg, var(--jade), var(--gold)); opacity: .0; transition: opacity .25s ease;
}
.feature:hover { transform: translateY(-5px); box-shadow: 0 1px 0 rgba(255, 255, 255, .95) inset, 0 30px 52px -30px rgba(6, 18, 10, .62); }
.feature:hover::before { opacity: 1; }
.feature h3 { font-size: 20px; margin-bottom: 8px; }
.feature p { color: var(--muted); font-size: 15.5px; }
.status-row { margin-top: 26px; }

/* ---------- 下载区 ---------- */
/* 平台清单写在 index.html 的 .dl-group 里（脚本不跑也照样能看能点），这里只管排版。
   对应 JS 见 main.js 的「下载区」：平台切换按钮、按设备推荐、data-bytes 换算体积。 */
.section-dl { border-top: 1px solid var(--line); }
.dl {
  position: relative; overflow: hidden; padding: 26px 30px 30px;
  background: var(--card); border: 1px solid var(--line); border-radius: 22px;
  box-shadow: 0 1px 0 rgba(255, 255, 255, .95) inset, 0 30px 60px -34px rgba(6, 18, 10, .55),
              0 4px 12px -6px rgba(6, 18, 10, .22);
}
.dl::before {
  content: ""; position: absolute; left: 0; right: 0; top: 0; height: 3px;
  background: linear-gradient(90deg, var(--jade), var(--gold), var(--cinnabar));
}
.dl-bar { padding-bottom: 18px; border-bottom: 1px dashed rgba(22, 36, 27, .16); }
.dl-bar-ver { display: flex; flex-wrap: wrap; align-items: baseline; gap: 12px; }
/* 「版本」二字是装饰，交给 CSS，DOM 里只留版本号，JS 取版本号就不用再切字符串 */
.dl-ver-no { font-family: var(--serif); font-size: 36px; line-height: 1; }
.dl-ver-no::before {
  content: "版本"; font-family: var(--sans); font-size: 13px; font-weight: 400;
  color: var(--muted); letter-spacing: .06em; margin-right: 8px;
}
.dl-bar-date { font-size: 14px; color: var(--muted); }

.chip { display: inline-flex; align-items: center; font-size: 12.5px; letter-spacing: .04em; padding: 3px 12px; border-radius: 999px; white-space: nowrap; }
.chip-cinnabar { background: rgba(178, 58, 43, .12); color: var(--cinnabar); }
.chip-rec { background: rgba(200, 169, 106, .24); color: #805f22; }

/* 平台切换：JS 生成按钮，脚本不生效时不占位，五个平台自上而下全列出 */
.dl-switch { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 10px; margin: 22px 0 26px; }
.dl-tile {
  appearance: none; cursor: pointer; text-align: left; font: inherit; color: inherit;
  padding: 12px 15px; border-radius: 14px; border: 1px solid var(--line);
  background: linear-gradient(180deg, #fffef9, rgba(22, 36, 27, .035));
  transition: transform .2s ease, border-color .2s ease, box-shadow .2s ease, background .2s ease, color .2s ease;
}
.dl-tile:hover { transform: translateY(-2px); border-color: rgba(178, 58, 43, .38); }
.dl-tile.is-active {
  background: linear-gradient(180deg, var(--deep-2), var(--deep)); color: var(--on-deep);
  border-color: rgba(200, 169, 106, .55); box-shadow: 0 18px 30px -20px rgba(6, 18, 10, .8);
}
.dl-tile-name { display: block; font-family: var(--serif); font-size: 18px; font-weight: 700; }
.dl-tile-avail { display: block; font-size: 12.5px; letter-spacing: .02em; color: var(--muted); margin-top: 2px; }
.dl-tile.is-active .dl-tile-avail { color: var(--on-deep-muted); }
.dl-tile.is-rec .dl-tile-avail { color: #a98c4e; font-weight: 600; }

.dl-group-head { display: flex; flex-wrap: wrap; align-items: baseline; gap: 6px 16px; }
.dl-group-title { display: inline-flex; align-items: center; gap: 12px; font-size: 24px; }
/* 「为你推荐」是 JS 按来访设备加的装饰标记，没有 JS 就不出现 */
.dl-group-title .chip-rec { font-size: 12px; padding: 2px 10px; }
.dl-req { font-size: 14.5px; color: var(--muted); }
.dl-hint {
  margin-top: 10px; padding: 4px 0 4px 14px; font-size: 14.5px; color: var(--muted);
  border-left: 2px solid rgba(200, 169, 106, .7);
}
.dl-hint code { font-family: ui-monospace, Consolas, monospace; font-size: .92em; background: rgba(22, 36, 27, .07); padding: 1px 5px; border-radius: 5px; }

.dl-list { display: grid; gap: 10px; margin-top: 18px; }
.dl-row {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px 20px;
  padding: 15px 18px; border: 1px solid var(--line); border-radius: 14px;
  background: rgba(22, 36, 27, .025);
}
.dl-row-info { flex: 1 1 260px; min-width: 0; }
.dl-row-info b { display: block; font-family: var(--serif); font-size: 18.5px; }
.dl-row-info small { display: block; margin-top: 3px; font-size: 13.5px; color: var(--muted); }
.dl-row-btn {
  display: inline-flex; align-items: center; gap: 8px; white-space: nowrap;
  font-size: 15px; font-weight: 600; text-decoration: none; color: var(--ink);
  padding: 10px 22px; border-radius: 999px; border: 1px solid rgba(22, 36, 27, .22);
  background: var(--card); transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease, background .18s ease;
}
.dl-row-btn::before {
  content: ""; width: 13px; height: 13px; background: currentColor;
  clip-path: polygon(38% 0, 62% 0, 62% 52%, 100% 52%, 50% 100%, 0 52%, 38% 52%);
}
.dl-row-btn[data-kind="web"]::before {
  clip-path: polygon(28% 4%, 72% 4%, 72% 56%, 100% 56%, 50% 100%, 0 56%, 28% 56%);
  transform: rotate(90deg);
}
.dl-row-btn:hover { transform: translateY(-2px); border-color: var(--cinnabar); color: var(--cinnabar); }
.dl-row-size { font-style: normal; font-weight: 600; font-size: 13.5px; opacity: .8; }
.dl-row-size:not(:empty)::before { content: "·"; margin-right: 7px; opacity: .6; }

/* 推荐那一档：压深背景，让「点哪个」在五种平台里一眼成立 */
.dl-row.is-primary {
  background: linear-gradient(135deg, var(--deep-2), var(--deep)); color: var(--on-deep);
  border-color: rgba(11, 26, 18, .32); box-shadow: 0 20px 36px -28px rgba(6, 18, 10, .78);
}
.dl-row.is-primary .dl-row-info small { color: var(--on-deep-muted); }
.dl-row.is-primary .dl-row-btn {
  background: linear-gradient(180deg, var(--cinnabar-2), var(--cinnabar)); color: #fff; border-color: transparent;
  box-shadow: 0 1px 0 rgba(255, 255, 255, .3) inset, 0 14px 26px -14px rgba(178, 58, 43, .9);
}
.dl-row.is-primary .dl-row-btn:hover { color: #fff; }

.dl-row.is-soon { background: transparent; border-style: dashed; }
.dl-row-tag { font-size: 13px; color: var(--muted); padding: 7px 15px; border-radius: 999px; border: 1px dashed rgba(22, 36, 27, .28); }

.dl-foot-note { margin-top: 22px; font-size: 14px; color: var(--muted); max-width: 82ch; }
.dl-foot-note a { color: var(--cinnabar); font-weight: 600; text-decoration: none; border-bottom: 1px solid rgba(178, 58, 43, .35); }
.dl-foot-note a:hover { border-bottom-color: var(--cinnabar); }

/* ---------- 导出 ---------- */
/* 与桌面端相邻，都是宣纸底：加一道分隔线，否则两段会糊成一整块 */
.section-export { border-top: 1px solid var(--line); }
.feature p.format-line {
  font-family: ui-monospace, Consolas, monospace;
  font-size: 13.5px; letter-spacing: .02em; color: var(--cinnabar);
  margin: 0 0 10px; line-height: 1.45;
}
.feature a { color: var(--cinnabar); font-weight: 600; border-bottom: 1px solid rgba(178, 58, 43, .35); }
.feature a:hover { border-bottom-color: var(--cinnabar); }

/* ---------- 路线图 ---------- */
.roadmap { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 26px; }
.road-col h3 { display: flex; align-items: center; gap: 10px; font-size: 21px; margin-bottom: 16px; }
.dot { width: 10px; height: 10px; border-radius: 50%; display: inline-block; }
.dot-done { background: var(--jade); }
.dot-soon { background: var(--gold); }
.dot-open { background: var(--cinnabar-2); }
.road-col ul li {
  position: relative; padding: 10px 0 10px 22px; font-size: 16px; color: #c3d1be;
  border-bottom: 1px solid rgba(233, 239, 230, .09);
}
.road-col ul li::before { content: ""; position: absolute; left: 2px; top: 19px; width: 8px; height: 1.5px; background: rgba(233, 239, 230, .4); }
.road-col .btn { margin-top: 18px; }

/* ---------- 资源 ---------- */
.resource-grid { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 14px; }
.resource-grid a {
  display: block; text-decoration: none; background: linear-gradient(180deg, #fffef9, var(--card));
  border: 1px solid var(--line); border-radius: 14px; padding: 20px 20px 18px;
  box-shadow: 0 1px 0 rgba(255, 255, 255, .95) inset, 0 12px 26px -24px rgba(6, 18, 10, .6);
  transition: transform .2s ease, border-color .2s ease, box-shadow .2s ease;
}
.resource-grid a:hover { transform: translateY(-4px); border-color: rgba(178, 58, 43, .45); box-shadow: 0 1px 0 rgba(255, 255, 255, .95) inset, 0 24px 40px -28px rgba(6, 18, 10, .75); }
.resource-grid span { font-family: var(--serif); font-size: 18px; font-weight: 700; display: block; }
.resource-grid small { display: block; margin-top: 6px; color: var(--muted); font-size: 13.5px; line-height: 1.6; }
.resource-links { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 26px; }
.resource-links a {
  text-decoration: none; font-size: 14.5px; padding: 8px 16px; border-radius: 999px;
  background: rgba(22, 36, 27, .06); border: 1px solid var(--line); transition: background .2s ease;
}
.resource-links a:hover { background: rgba(22, 36, 27, .12); }

/* ---------- FAQ ---------- */
.section-faq { padding-top: 0; }
.faq-list details {
  border-bottom: 1px solid var(--line); background: var(--card);
  border-radius: 12px; margin-bottom: 10px; border: 1px solid var(--line);
}
.faq-list summary {
  cursor: pointer; list-style: none; padding: 20px 52px 20px 24px;
  font-family: var(--serif); font-size: 19px; font-weight: 700; position: relative;
}
.faq-list summary::-webkit-details-marker { display: none; }
.faq-list summary::after {
  content: ""; position: absolute; right: 24px; top: 50%; width: 12px; height: 12px;
  border-right: 2px solid var(--cinnabar); border-bottom: 2px solid var(--cinnabar);
  transform: translateY(-70%) rotate(45deg); transition: transform .22s ease;
}
.faq-list details[open] summary::after { transform: translateY(-30%) rotate(225deg); }
.faq-list details p { padding: 0 24px 22px; color: var(--muted); font-size: 16px; }

/* ---------- 结尾 CTA ---------- */
.cta-band { background: linear-gradient(120deg, var(--deep-3), var(--deep)); color: var(--on-deep); padding: 70px 0; }
.cta-inner { display: flex; align-items: center; justify-content: space-between; gap: 30px; flex-wrap: wrap; }
.cta-inner h2 { font-size: clamp(26px, 3vw, 36px); }
.cta-inner p { color: #bccbb7; margin-top: 10px; }

/* ---------- 页脚 ---------- */
.site-footer { background: #07130c; color: var(--on-deep-muted); padding: 60px 0 28px; }
.footer-top { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(0, 1.4fr); gap: 40px; padding-bottom: 34px; border-bottom: 1px solid rgba(233, 239, 230, .1); }
.footer-brand { display: flex; gap: 16px; align-items: flex-start; }
.footer-brand img { width: 56px; height: 56px; }
.footer-name { font-family: var(--serif); font-size: 22px; color: var(--on-deep); }
.footer-name span { font-size: 14px; letter-spacing: .18em; color: var(--on-deep-muted); margin-left: 8px; }
.footer-slogan { margin-top: 8px; font-size: 14.5px; max-width: 26em; }
.footer-cols { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 22px; }
.footer-cols h4 { font-size: 15px; color: var(--on-deep); letter-spacing: .08em; margin-bottom: 12px; font-family: var(--sans); font-weight: 600; }
.footer-cols a { display: block; text-decoration: none; font-size: 14.5px; padding: 5px 0; transition: color .18s ease; }
.footer-cols a:hover { color: var(--on-deep); }
.footer-cols address { font-style: normal; font-size: 14px; line-height: 1.7; margin-top: 8px; }
.footer-bottom { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px; padding-top: 22px; font-size: 13.5px; }
.footer-bottom a { color: inherit; }

/* ---------- 动效 ---------- */
/* 隐藏态只在 JS 可用时生效（<head> 里的内联脚本给 <html> 加 .js），
   脚本挂掉或打印时内容仍然可见。 */
.js .reveal { opacity: 0; transform: translateY(22px); transition: opacity .7s ease, transform .7s ease; }
.js .reveal.is-in { opacity: 1; transform: none; }
/* 没有 JS 时五份平台清单自上而下全铺开，链接照样能点；有 JS 才切成一次只显示一档 */
.js .dl-group { display: none; }
.js .dl-group.is-active { display: block; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .001ms !important; animation-iteration-count: 1 !important; transition-duration: .001ms !important; }
  .js .reveal { opacity: 1; transform: none; }
}

/* ---------- 响应式 ---------- */
@media (max-width: 1080px) {
  .dl-switch { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .hero-inner { grid-template-columns: 1fr; gap: 46px; }
  .hero-visual { max-width: 640px; }
  .sheet-stack { height: 300px; }
  .sheet-back-a { width: 64%; left: 0; }
  .sheet-back-b { width: 62%; right: 0; }
  .sheet-front { width: 84%; left: 8%; }
  .resource-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .feature-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .ai-flow, .roadmap { grid-template-columns: 1fr; }
  .ai-showcase { grid-template-columns: 1fr; }
  .ai-arrow { transform: rotate(90deg); justify-self: center; }
}

@media (max-width: 860px) {
  body { font-size: 16px; }
  .nav-toggle { display: block; }
  .site-nav {
    position: absolute; left: 0; right: 0; top: 72px; flex-direction: column; align-items: stretch;
    gap: 2px; padding: 14px 24px 22px; margin: 0;
    background: rgba(8, 20, 14, .98); border-bottom: 1px solid rgba(233, 239, 230, .14);
    display: none;
  }
  .site-nav.is-open { display: flex; }
  .site-nav a { padding: 13px 10px; font-size: 16px; border-radius: 10px; }
  .site-nav .nav-cta { margin: 12px 0 0; justify-content: center; }
  .section { padding: 70px 0; }
  /* 窄屏不做叠放，三张谱改成竖着排，每张都看得清 */
  .sheet-stack { height: auto; display: grid; gap: 16px; }
  .sheet, .hero-visual:hover .sheet { position: static; width: auto; transform: none; }
  .hero-visual:hover .sheet-back-a, .hero-visual:hover .sheet-back-b { transform: none; }
  .stack-note { margin-top: 18px; text-align: left; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .stat { border-bottom: 1px solid rgba(233, 239, 230, .1); }
  .stat:nth-child(2n) { border-right: 0; }
  .grid-2, .notation-list, .feature-grid { grid-template-columns: 1fr; }
  .notation-paper { padding: 24px 16px 14px; }
  /* 窄屏上把谱条横向滚动，而不是缩成一团看不清的符号 */
  .score-scroll img { width: auto; min-width: 100%; max-width: none; }
  .notation-paper figcaption { flex-direction: column; gap: 6px; }
  .notation-source { white-space: normal; }
  .footer-top { grid-template-columns: 1fr; }
  .hero { padding-top: 52px; }
  .seg { width: 100%; justify-content: space-between; }
  .seg-btn { padding: 9px 14px; font-size: 15px; }
  .dl { padding: 22px 18px 24px; }
  .dl-switch { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .dl-bar-note { max-width: none; }
  .dl-ver-no { font-size: 30px; }
  .dl-row-info { flex-basis: 100%; }
}

@media (max-width: 520px) {
  .dl-switch { grid-template-columns: 1fr; }
  /* 窄屏把「下载」按钮拉满宽，横向的可点区域比留白重要 */
  .dl-row-btn { flex: 1 1 auto; justify-content: center; }
  .hero-dl-go { width: 100%; justify-content: center; }
  .hero-dl-tabs { display: flex; width: 100%; border-radius: 14px; }
  .hero-dl-tab { flex: 1 1 auto; justify-content: center; }
  .resource-grid { grid-template-columns: 1fr; }
  .footer-cols { grid-template-columns: 1fr 1fr; }
  .hero-actions .btn { width: 100%; justify-content: center; }
  .cta-inner .btn { width: 100%; justify-content: center; }
}