:root {
  --bg: #090b10;
  --surface: #0f1219;
  --surface-2: #151923;
  --line: #222838;
  --text: #e7eaf1;
  --body: #c3c8d4;
  --muted: #8b93a7;
  --faint: #5d6579;
  --accent: #7cc4ff;
  --warm: #ffc86b;
  --good: #5fe0a0;
  --bad: #ff7a7a;
  --mono: "SF Mono", ui-monospace, Menlo, Consolas, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --serif: "Times New Roman", "STIX Two Text", Georgia, "Songti SC", serif;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html, body {
  margin: 0;
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font: 14px/1.6 var(--sans);
  -webkit-font-smoothing: antialiased;
}

.app {
  display: grid;
  grid-template-columns: 216px minmax(0, 1fr) 380px;
  height: 100vh;
}

/* ---------- 导航 ---------- */
.nav {
  background: var(--surface);
  border-right: 1px solid var(--line);
  padding: 20px 12px;
  overflow-y: auto;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 0 8px 18px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--line);
}
.brand-mark {
  width: 28px;
  height: 28px;
  flex-shrink: 0;
  border-radius: 50%;
  background: conic-gradient(from 200deg, #ff5b5b, #ffc14d, #f6ff6b, #5fe08a, #4dc9ff, #6b6bff, #c25bff, #ff5b5b);
  box-shadow: 0 0 18px rgba(124, 196, 255, .35);
}
.brand b { display: block; white-space: nowrap; font-size: 15px; letter-spacing: .02em; }
.brand small { display: block; color: var(--faint); font: 10.5px var(--mono); letter-spacing: .1em; text-transform: uppercase; }

.nav-group { margin-bottom: 18px; }
.nav-chapter {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 0 10px 6px;
  font-size: 12px;
  color: var(--muted);
}
.nav-chapter span { font: 11px var(--mono); color: var(--faint); }
.nav a {
  display: block;
  padding: 7px 10px;
  border-radius: 8px;
  color: var(--text);
  text-decoration: none;
  font-size: 13.5px;
  opacity: .75;
  transition: background .15s, opacity .15s, color .15s;
}
.nav a:hover { background: var(--surface-2); opacity: 1; }
.nav a.active { background: rgba(124, 196, 255, .12); color: var(--accent); opacity: 1; }
.nav a.disabled { opacity: .3; pointer-events: none; font-size: 13px; padding-top: 4px; padding-bottom: 4px; }

/* ---------- 3D 舞台 ---------- */
.stage-wrap { position: relative; min-height: 0; }
#stage { position: absolute; inset: 0; overflow: hidden; }
#stage canvas { display: block; }
.labels { position: absolute; inset: 0; pointer-events: none; }

.stage-tools { position: absolute; top: 14px; right: 14px; display: flex; gap: 8px; }
.stage-tools button {
  font: 12.5px var(--sans);
  color: var(--muted);
  background: rgba(15, 18, 25, .8);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 6px 12px;
  cursor: pointer;
  backdrop-filter: blur(6px);
  transition: color .15s, border-color .15s;
}
.stage-tools button:hover { color: var(--text); border-color: #39415a; }
.stage-hint {
  position: absolute;
  left: 16px;
  bottom: 14px;
  font-size: 12px;
  color: var(--faint);
  pointer-events: none;
}

/* 3D 标注 */
.lbl {
  font: 12px/1.3 var(--sans);
  color: var(--text);
  background: rgba(12, 15, 22, .72);
  border: 1px solid rgba(255, 255, 255, .08);
  border-radius: 6px;
  padding: 2px 7px;
  white-space: nowrap;
}
.lbl.plain { background: none; border: 0; padding: 0; color: var(--muted); }
.lbl.mono { font-family: var(--mono); font-size: 11.5px; }
.lbl.warm { color: var(--warm); }
.lbl.cool { color: var(--accent); }
.lbl.alert { color: #fff; background: rgba(255, 92, 92, .88); border-color: transparent; font-weight: 600; font-size: 13px; padding: 3px 9px; }

/* ---------- 右侧面板 ---------- */
.panel {
  background: var(--surface);
  border-left: 1px solid var(--line);
  padding: 26px 24px 48px;
  overflow-y: auto;
}
.chapter { font: 11px var(--mono); letter-spacing: .12em; color: var(--accent); }
h1 { font-size: 24px; font-weight: 650; margin: 6px 0 8px; letter-spacing: .01em; }
.lead { color: var(--muted); margin: 0 0 18px; }

.card {
  background: var(--surface-2);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 14px;
  margin-bottom: 12px;
}
.card:empty { display: none; }

.ctl[hidden] { display: none; }
.ctl + .ctl { margin-top: 14px; }
.ctl-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 7px;
}
.ctl-head output { font-family: var(--mono); font-size: 12.5px; color: var(--text); }

input[type=range] {
  -webkit-appearance: none;
  appearance: none;
  display: block;
  width: 100%;
  height: 4px;
  margin: 8px 0 4px;
  border-radius: 4px;
  outline: none;
  background: linear-gradient(to right, var(--accent) var(--p, 50%), #2a3142 var(--p, 50%));
}
input[type=range]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #fff;
  border: 3px solid var(--accent);
  box-shadow: 0 0 0 4px rgba(124, 196, 255, .15);
  cursor: pointer;
}
input[type=range]::-moz-range-thumb {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: #fff;
  border: 3px solid var(--accent);
  cursor: pointer;
}

.seg {
  display: flex;
  gap: 3px;
  padding: 3px;
  background: #0b0e14;
  border: 1px solid var(--line);
  border-radius: 9px;
}
.seg button {
  flex: 1;
  border: 0;
  background: none;
  color: var(--muted);
  font: 13px var(--sans);
  padding: 6px 4px;
  border-radius: 6px;
  cursor: pointer;
  transition: background .15s, color .15s;
}
.seg button:hover { color: var(--text); }
.seg button.on { background: #222a3a; color: var(--text); }

.readout { display: grid; gap: 7px; }
.stat { display: flex; justify-content: space-between; gap: 12px; font-size: 13px; }
.stat span { color: var(--muted); flex-shrink: 0; }
.stat b { font: 500 12.5px/1.6 var(--mono); text-align: right; }
.stat[data-tone=good] b { color: var(--good); }
.stat[data-tone=bad] b { color: var(--bad); }
.stat[data-tone=warm] b { color: var(--warm); }
.swatch { display: inline-block; width: 10px; height: 10px; border-radius: 3px; margin-right: 6px; vertical-align: -1px; }

.formula {
  margin: 18px 0 6px;
  padding: 10px 14px;
  border-left: 2px solid var(--warm);
  border-radius: 0 8px 8px 0;
  background: linear-gradient(90deg, rgba(255, 200, 107, .08), transparent);
  font: 17px/1.7 var(--serif);
}
.formula small { display: block; font: 12px/1.6 var(--sans); color: var(--muted); }

.section h2 {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: .12em;
  color: var(--faint);
  margin: 24px 0 8px;
}
.section p { margin: 0 0 10px; color: var(--body); }
.section p b { color: var(--text); font-weight: 600; }
.section ul { margin: 0; padding-left: 18px; color: var(--body); }
.section li { margin-bottom: 6px; }
.section li b { color: var(--text); font-weight: 600; }

.section[hidden] { display: none; }
.faq details {
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface-2);
  margin-bottom: 8px;
}
.faq summary {
  list-style: none;
  cursor: pointer;
  padding: 10px 14px;
  font-weight: 600;
  color: var(--text);
  display: flex;
  justify-content: space-between;
  gap: 12px;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: '+'; color: var(--muted); font: 16px var(--mono); }
.faq details[open] summary::after { content: '−'; }
.faq details p { padding: 0 14px; }
.faq details p:last-child { padding-bottom: 4px; }

/* ---------- 响应式 ---------- */
@media (max-width: 1180px) {
  .app { grid-template-columns: 188px minmax(0, 1fr) 330px; }
}
@media (max-width: 860px) {
  .app { display: flex; flex-direction: column; height: auto; min-height: 100vh; }
  .nav {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 10px 16px;
    border-right: 0;
    border-bottom: 1px solid var(--line);
    overflow-x: auto;
  }
  .brand { padding: 0; margin: 0; border: 0; flex-shrink: 0; }
  .brand small { display: none; }
  #nav, .nav-group { display: flex; align-items: center; gap: 2px; margin: 0; }
  .nav-chapter, .nav a.disabled { display: none; }
  .nav a { white-space: nowrap; }
  .stage-wrap { height: 58vh; flex-shrink: 0; }
  .stage-hint { display: none; }
  .panel { border-left: 0; padding: 20px 16px 40px; }
}