:root {
  --bg: #08090b;
  --text: #e7eaee;
  --muted: #878e99;
  --faint: #5d636d;
  --accent: #a6c8e0;
  --accent-deep: #6f9fc2;
  --line: rgba(255, 255, 255, .08);
  --line-strong: rgba(255, 255, 255, .16);
  --glass: rgba(255, 255, 255, .04);
  --glass-hi: rgba(255, 255, 255, .07);
  --ok: #8fd6a8;
  --radius: 16px;
  --mono: "JetBrains Mono", ui-monospace, monospace;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 400 15px/1.6 Inter, system-ui, -apple-system, sans-serif;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
a { color: inherit; }
img, svg { display: block; }
::selection { background: rgba(166, 200, 224, .3); }

/* starfield + glow */
#stars { position: fixed; inset: 0; z-index: -2; pointer-events: none; }
.glow {
  position: fixed; z-index: -1; pointer-events: none;
  width: 900px; height: 600px; left: 50%; top: -320px; transform: translateX(-50%);
  background: radial-gradient(closest-side, rgba(166, 200, 224, .10), transparent);
}

.container { width: 100%; max-width: 1080px; margin: 0 auto; padding: 0 20px; }

/* nav */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: rgba(8, 9, 11, .72);
  backdrop-filter: blur(14px) saturate(140%);
  -webkit-backdrop-filter: blur(14px) saturate(140%);
  border-bottom: 1px solid var(--line);
}
.nav-in { display: flex; align-items: center; gap: 24px; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 600; text-decoration: none; letter-spacing: -.01em; }
.brand img { border-radius: 6px; }
.brand .sub { color: var(--muted); font-weight: 500; }
.nav-links { display: flex; gap: 22px; margin-left: auto; }
.nav-links a { color: var(--muted); text-decoration: none; font-size: 14px; transition: color .15s; }
.nav-links a:hover, .nav-links a[aria-current="page"] { color: var(--text); }

/* buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  height: 40px; padding: 0 16px; border-radius: 12px;
  font: 600 14px Inter, sans-serif; text-decoration: none; white-space: nowrap;
  border: 1px solid var(--line); background: var(--glass); color: var(--text);
  cursor: pointer; transition: background .15s, border-color .15s, transform .1s;
}
.btn:hover { background: var(--glass-hi); border-color: var(--line-strong); }
.btn:active { transform: scale(.98); }
.btn-primary { background: var(--glass-hi); border-color: var(--line-strong); }
.btn-accent { background: var(--accent); color: #0a1118; border-color: transparent; }
.btn-accent:hover { background: #bcd7ea; border-color: transparent; }
.btn-lg { height: 46px; padding: 0 20px; font-size: 15px; }
.btn svg { flex: none; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* type */
.eyebrow { font: 400 12px var(--mono); color: var(--muted); margin: 0 0 12px; letter-spacing: .02em; }
h1, h2, h3 { letter-spacing: -.025em; margin: 0; font-weight: 600; }
.hero { padding: 96px 0 56px; }
.hero h1 { font-size: clamp(38px, 6.4vw, 64px); line-height: 1.04; max-width: 14ch; }
.hero h1 em { font-style: normal; color: var(--accent); }
.hero p.lead { color: var(--muted); font-size: 17px; max-width: 54ch; margin: 20px 0 32px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; }
.section { padding: 40px 0; }
.section h2 { font-size: clamp(24px, 3.2vw, 30px); margin-bottom: 8px; }
.section .sub { color: var(--muted); margin: 0 0 24px; }

/* stats strip */
.stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-top: 48px; max-width: 640px; }
.stat { border: 1px solid var(--line); background: var(--glass); border-radius: 14px; padding: 14px 16px; }
.stat b { display: block; font-size: 22px; font-weight: 600; letter-spacing: -.02em; }
.stat span { color: var(--muted); font-size: 13px; }

/* cards */
.card { border: 1px solid var(--line); background: var(--glass); border-radius: var(--radius); padding: 24px; }

/* index URL box */
.indexbox { display: flex; align-items: center; gap: 12px; padding: 18px 20px; }
.indexbox .ic { width: 40px; height: 40px; border-radius: 10px; background: var(--glass-hi); border: 1px solid var(--line); display: grid; place-items: center; color: var(--accent); flex: none; }
.indexbox .txt { min-width: 0; flex: 1; }
.indexbox .lbl { font-size: 13px; color: var(--muted); }
.indexbox code { display: block; font: 500 14px var(--mono); color: var(--text); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

/* toolbar */
.toolbar { display: flex; gap: 12px; align-items: center; margin-bottom: 16px; }
.search { position: relative; flex: 1; }
.search svg { position: absolute; left: 14px; top: 50%; transform: translateY(-50%); color: var(--faint); }
.search input {
  width: 100%; height: 46px; padding: 0 14px 0 42px; border-radius: 12px;
  border: 1px solid var(--line); background: var(--glass); color: var(--text);
  font: 400 15px Inter, sans-serif; transition: border-color .15s, background .15s;
}
.search input::placeholder { color: var(--faint); }
.search input:focus { outline: none; border-color: var(--line-strong); background: var(--glass-hi); }
.count { font: 400 12px var(--mono); color: var(--muted); white-space: nowrap; }

/* song rows */
.songs { display: grid; gap: 10px; }
.song {
  display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 16px;
  padding: 14px 16px 14px 14px; border-radius: var(--radius);
  border: 1px solid var(--line); background: var(--glass);
  transition: border-color .15s, background .15s;
}
.song:hover { border-color: var(--line-strong); }
.song.playing { border-color: rgba(166, 200, 224, .35); background: rgba(166, 200, 224, .05); }
.play {
  width: 48px; height: 48px; border-radius: 12px; border: 1px solid var(--line);
  background: var(--glass-hi); color: var(--text); display: grid; place-items: center; cursor: pointer; flex: none;
  transition: background .15s, color .15s;
}
.play:hover { background: rgba(255, 255, 255, .1); }
.song.playing .play { background: var(--accent); color: #0a1118; border-color: transparent; }
.info { min-width: 0; }
.title { display: flex; align-items: baseline; gap: 10px; min-width: 0; }
.title h3 { font-size: 16px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.artist { color: var(--muted); font-size: 14px; }
.meta { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 8px; }
.chip {
  display: inline-flex; align-items: center; gap: 6px; height: 24px; padding: 0 9px;
  border-radius: 999px; border: 1px solid var(--line); background: transparent;
  font: 500 12px var(--mono); color: var(--muted);
}
button.chip { cursor: pointer; color: var(--text); transition: border-color .15s, background .15s; }
button.chip:hover { border-color: var(--line-strong); background: var(--glass-hi); }
.chip.tag { color: var(--ok); border-color: rgba(143, 214, 168, .25); }
.bar { grid-column: 2 / -1; height: 3px; border-radius: 3px; background: var(--line); overflow: hidden; margin-top: -4px; cursor: pointer; display: none; }
.song.playing .bar, .song.paused .bar { display: block; }
.bar i { display: block; height: 100%; width: 0; background: var(--accent); }
.actions { display: flex; gap: 8px; }
.empty { text-align: center; color: var(--muted); padding: 48px 0; border: 1px dashed var(--line); border-radius: var(--radius); }

/* steps (landing) */
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.step .n { font: 500 12px var(--mono); color: var(--accent); }
.step h3 { font-size: 16px; margin: 10px 0 6px; }
.step p { color: var(--muted); margin: 0; font-size: 14px; }

/* tutorial */
.doc { display: grid; grid-template-columns: 220px 1fr; gap: 48px; padding: 56px 0 24px; }
.toc { position: sticky; top: 88px; align-self: start; }
.toc a { display: block; color: var(--muted); text-decoration: none; font-size: 14px; padding: 6px 0 6px 14px; border-left: 1px solid var(--line); transition: color .15s, border-color .15s; }
.toc a:hover, .toc a.active { color: var(--text); border-color: var(--accent); }
.doc h1 { font-size: clamp(32px, 5vw, 46px); line-height: 1.08; }
.doc .lead { color: var(--muted); font-size: 17px; margin: 16px 0 8px; max-width: 60ch; }
.doc section { padding-top: 40px; scroll-margin-top: 80px; }
.doc h2 { font-size: 24px; margin-bottom: 12px; }
.doc h3 { font-size: 16px; margin: 20px 0 8px; }
.doc p, .doc li { color: #c4c9d1; }
.doc p { margin: 0 0 12px; max-width: 68ch; }
.doc ol, .doc ul { padding-left: 20px; margin: 0 0 12px; max-width: 68ch; }
.doc li { margin: 6px 0; }
.doc li::marker { color: var(--faint); }
.doc b, .doc strong { color: var(--text); font-weight: 600; }
.doc code { font: 500 13px var(--mono); background: var(--glass-hi); border: 1px solid var(--line); border-radius: 6px; padding: 1px 6px; color: var(--text); word-break: break-word; }
.path { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; margin: 8px 0 14px; }
.path span { font: 500 12.5px var(--mono); padding: 5px 10px; border-radius: 8px; background: var(--glass-hi); border: 1px solid var(--line); }
.path i { color: var(--faint); font-style: normal; }
.callout { display: flex; gap: 12px; padding: 14px 16px; border-radius: 12px; border: 1px solid rgba(166, 200, 224, .22); background: rgba(166, 200, 224, .05); margin: 16px 0; }
.callout svg { color: var(--accent); flex: none; margin-top: 3px; }
.callout p { margin: 0; }
.tabs { display: inline-flex; gap: 4px; padding: 4px; border-radius: 12px; border: 1px solid var(--line); background: var(--glass); margin: 4px 0 16px; }
.tabs button { height: 34px; padding: 0 14px; border-radius: 9px; border: 0; background: transparent; color: var(--muted); font: 600 13px Inter, sans-serif; cursor: pointer; }
.tabs button[aria-selected="true"] { background: var(--glass-hi); color: var(--text); }
[data-panel][hidden] { display: none; }
.faq details { border: 1px solid var(--line); background: var(--glass); border-radius: 12px; padding: 0 16px; margin-bottom: 8px; }
.faq summary { cursor: pointer; padding: 14px 0; font-weight: 600; list-style: none; display: flex; justify-content: space-between; gap: 12px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--muted); font-weight: 400; }
.faq details[open] summary::after { content: "−"; }
.faq details p { margin: 0 0 14px; }

/* footer */
footer { border-top: 1px solid var(--line); margin-top: 72px; }
.foot { display: flex; align-items: center; gap: 20px; height: 72px; color: var(--muted); font-size: 13px; }
.foot nav { display: flex; gap: 18px; margin-left: auto; }
.foot a { color: var(--muted); text-decoration: none; }
.foot a:hover { color: var(--text); }

/* toast */
.toast {
  position: fixed; left: 50%; bottom: 24px; transform: translate(-50%, 12px); z-index: 100;
  background: #1a1c20; border: 1px solid rgba(255, 255, 255, .12); color: var(--text);
  padding: 10px 16px; border-radius: 12px; font-size: 14px; display: flex; align-items: center; gap: 8px;
  opacity: 0; transition: opacity .2s, transform .2s; pointer-events: none;
  box-shadow: 0 10px 30px rgba(0, 0, 0, .4);
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }
.toast svg { color: var(--ok); }

.reveal { opacity: 0; transform: translateY(8px); transition: opacity .5s ease, transform .5s ease; }
.reveal.in { opacity: 1; transform: none; }

/* ---------- phone ---------- */
@media (max-width: 860px) {
  .doc { grid-template-columns: 1fr; gap: 0; padding-top: 32px; }
  .toc { position: static; display: flex; gap: 6px; overflow-x: auto; padding-bottom: 8px; margin: 0 -20px 8px; padding-left: 20px; padding-right: 20px; scrollbar-width: none; }
  .toc::-webkit-scrollbar { display: none; }
  .toc a { border: 1px solid var(--line); border-radius: 999px; padding: 6px 12px; white-space: nowrap; background: var(--glass); }
  .toc a.active { border-color: var(--line-strong); }
  .steps { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  body { font-size: 15px; }
  .container { padding: 0 16px; }
  .nav-in { height: 58px; gap: 12px; }
  .nav-links { gap: 16px; }
  .nav-links a.hide-sm { display: none; }
  .nav-cta span { display: none; }
  .nav-cta { width: 40px; padding: 0; }
  .hero { padding: 56px 0 32px; }
  .hero p.lead { font-size: 16px; }
  .hero-actions .btn { flex: 1 1 100%; }
  .stats { gap: 8px; margin-top: 32px; }
  .stat { padding: 12px; }
  .stat b { font-size: 18px; }
  .stat span { font-size: 12px; }
  .indexbox { flex-wrap: wrap; }
  .indexbox .btn { width: 100%; }
  .toolbar { flex-direction: column; align-items: stretch; gap: 8px; }
  .count { text-align: right; }
  .song { grid-template-columns: auto 1fr; gap: 12px; padding: 12px; }
  .play { width: 44px; height: 44px; }
  .actions { grid-column: 1 / -1; }
  .actions .btn { flex: 1; height: 44px; }
  .bar { grid-column: 1 / -1; margin-top: 0; }
  .foot { flex-direction: column; justify-content: center; gap: 8px; height: auto; padding: 24px 0; }
  .foot nav { margin: 0; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
}

.doc > * { min-width: 0; }