/* =========================================================
 * GSAP 学习手册 · 时间轴台本 UI
 * 调色来自动画时间线（琥珀 playhead），不是通用深色后台。
 * ========================================================= */

:root {
  --void: #0b0f14;
  --panel: #151b24;
  --panel-2: #1c2430;
  --hairline: #2c3544;
  --playhead: #e8a020;
  --playhead-dim: rgba(232, 160, 32, 0.18);
  --signal: #8ec8e6;
  --ink: #e8eef6;
  --mute: #8a93a3;
  --track: #6ee7b7;
  --sidebar-w: 268px;
  --ruler-h: 32px;
  /* 不用 Google Fonts：.cn 访问常被拦，台本气质靠 PingFang + 等宽时间码 */
  --display: "Avenir Next", "Segoe UI", "PingFang SC", "Hiragino Sans GB", sans-serif;
  --body: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --mono: "SF Mono", "Menlo", "Consolas", "Sarasa Mono SC", monospace;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html, body {
  min-height: 100%;
  background: var(--void);
  color: var(--ink);
  font-family: var(--body);
  line-height: 1.7;
  font-size: 16px;
}

a { color: var(--signal); text-decoration: none; }
a:hover { color: #c5e6f7; text-decoration: underline; text-underline-offset: 3px; }

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

code, pre { font-family: var(--mono); }

/* ---------- 布局 ---------- */
.layout { display: flex; min-height: 100vh; }

.sidebar {
  width: var(--sidebar-w);
  flex-shrink: 0;
  background: #10151c;
  border-right: 1px solid var(--hairline);
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  padding: 22px 14px 48px;
}

.sidebar-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--display);
  font-weight: 700;
  font-size: 15px;
  letter-spacing: 0.04em;
  color: var(--ink);
  text-decoration: none;
}
.sidebar-brand:hover { color: var(--ink); text-decoration: none; }
.sidebar-brand svg { flex-shrink: 0; }

.sidebar-ver {
  font-family: var(--mono);
  font-size: 11px;
  color: var(--mute);
  margin: 8px 0 22px;
  letter-spacing: 0.04em;
}

.nav-group { margin-bottom: 20px; }
.nav-group h4 {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: #6b7382;
  margin-bottom: 8px;
  padding: 0 8px;
}
.nav-group a {
  display: grid;
  grid-template-columns: 44px 1fr;
  gap: 8px;
  align-items: baseline;
  padding: 7px 8px;
  border-radius: 2px;
  color: var(--mute);
  font-size: 13px;
  text-decoration: none;
  border-left: 2px solid transparent;
}
.nav-group a .tc {
  font-family: var(--mono);
  font-size: 10px;
  color: #5c6573;
}
.nav-group a:hover {
  background: var(--panel);
  color: var(--ink);
  text-decoration: none;
}
.nav-group a.active {
  background: var(--playhead-dim);
  color: var(--ink);
  border-left-color: var(--playhead);
}
.nav-group a.active .tc { color: var(--playhead); }

.main {
  flex: 1;
  min-width: 0;
  padding: 0 40px 80px;
}

.container { max-width: 1040px; padding-top: 8px; }

/* ---------- 帧尺（签名） ---------- */
.time-ruler {
  position: sticky;
  top: 0;
  z-index: 8;
  height: var(--ruler-h);
  margin: 0 -40px 28px;
  background:
    repeating-linear-gradient(
      90deg,
      var(--hairline) 0,
      var(--hairline) 1px,
      transparent 1px,
      transparent 8px
    ),
    repeating-linear-gradient(
      90deg,
      #3d4756 0,
      #3d4756 1px,
      transparent 1px,
      transparent 40px
    ),
    #10151c;
  border-bottom: 1px solid var(--hairline);
  overflow: hidden;
}
.time-ruler .playhead {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--playhead);
  box-shadow: 0 0 0 3px var(--playhead-dim);
  animation: playhead-run 9s linear infinite;
}
.time-ruler .playhead::before {
  content: "";
  position: absolute;
  top: 0;
  left: -5px;
  border-left: 6px solid transparent;
  border-right: 6px solid transparent;
  border-top: 7px solid var(--playhead);
}

@keyframes playhead-run {
  from { left: 8%; }
  to { left: 92%; }
}

@media (prefers-reduced-motion: reduce) {
  .time-ruler .playhead { animation: none; left: 28%; }
}

/* ---------- 首页英雄：活时间线 ---------- */
.hero-stage {
  position: relative;
  background: var(--panel);
  border: 1px solid var(--hairline);
  padding: 28px 28px 22px;
  margin-bottom: 36px;
}
.hero-kicker {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--playhead);
  margin-bottom: 12px;
}
.hero-stage h1 {
  font-family: var(--display);
  font-size: clamp(1.8rem, 4vw, 2.7rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 12px;
}
.hero-stage .lede {
  max-width: 40rem;
  color: var(--mute);
  font-size: 1.02rem;
}
.hero-meta {
  margin-top: 14px;
  font-family: var(--mono);
  font-size: 12px;
  color: #6b7382;
}

.mini-tl {
  margin-top: 28px;
  height: 72px;
  position: relative;
  background: var(--void);
  border: 1px solid var(--hairline);
}
.mini-tl .lane {
  position: absolute;
  left: 12px;
  right: 12px;
  top: 28px;
  height: 2px;
  background: var(--hairline);
}
.mini-tl .runner {
  position: absolute;
  top: 16px;
  left: 12px;
  width: 40px;
  height: 26px;
  background: var(--playhead);
  color: #1a1408;
  font-family: var(--mono);
  font-size: 10px;
  font-weight: 500;
  display: grid;
  place-items: center;
}

h1.page-title {
  font-family: var(--display);
  font-size: 2rem;
  letter-spacing: -0.03em;
  margin: 8px 0 8px;
}
.page-lead { color: var(--mute); margin-bottom: 28px; }

h2 {
  font-family: var(--display);
  font-size: 1.25rem;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin: 40px 0 14px;
  display: flex;
  align-items: baseline;
  gap: 12px;
}
h2 .tc {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--playhead);
  font-weight: 500;
}
h3 {
  font-size: 1.05rem;
  color: #c9d2de;
  margin: 22px 0 10px;
  font-weight: 600;
}
p { margin-bottom: 12px; }
ul, ol { margin: 0 0 16px 22px; color: var(--mute); }
li { margin: 4px 0; }

.note {
  background: var(--panel);
  border: 1px solid var(--hairline);
  border-left: 3px solid var(--playhead);
  padding: 12px 14px;
  color: #c5cdd8;
  font-size: 14px;
  margin: 14px 0 20px;
}
.warn {
  border-left-color: #d97777;
  color: #f0d0d0;
}

.demo-card {
  background: var(--panel);
  border: 1px solid var(--hairline);
  padding: 22px;
  margin-bottom: 20px;
}
.demo-title {
  font-family: var(--display);
  font-weight: 600;
  color: var(--playhead);
  margin-bottom: 6px;
}
.demo-desc { color: var(--mute); margin-bottom: 14px; font-size: 0.95rem; }
.demo-stage {
  background: var(--void);
  min-height: 120px;
  position: relative;
  overflow: hidden;
  margin-bottom: 14px;
  border: 1px dashed var(--hairline);
}

.box {
  width: 64px;
  height: 64px;
  background: var(--signal);
  color: var(--void);
  border-radius: 2px;
  position: absolute;
  top: 28px;
  left: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--mono);
  font-weight: 500;
  font-size: 11px;
  letter-spacing: 0.04em;
  user-select: none;
}
.box.green { background: var(--track); }
.box.orange { background: var(--playhead); color: #1a1408; }
.box.red { background: #e07a7a; color: #1a0c0c; }
.box.purple { background: #a78bfa; color: #12081c; }

.btn-group { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; }
.btn {
  padding: 8px 14px;
  border: 1px solid var(--hairline);
  border-radius: 2px;
  background: var(--panel-2);
  color: var(--ink);
  cursor: pointer;
  font-size: 13px;
  font-family: var(--body);
}
.btn:hover { border-color: var(--playhead); color: var(--playhead); }
.btn.secondary { background: transparent; }
.btn.ghost { background: transparent; }

pre {
  background: #080b10;
  padding: 14px 16px;
  overflow-x: auto;
  font-size: 12.5px;
  color: #d6e6c8;
  border: 1px solid var(--hairline);
  line-height: 1.55;
}
.inline-code {
  font-family: var(--mono);
  background: var(--panel-2);
  padding: 1px 6px;
  color: var(--playhead);
  font-size: 0.9em;
}

.prop-table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0 20px;
  font-size: 14px;
}
.prop-table th, .prop-table td {
  padding: 9px 12px;
  text-align: left;
  border-bottom: 1px solid var(--hairline);
  vertical-align: top;
}
.prop-table th {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--playhead);
  background: var(--panel-2);
}
.prop-table tr:hover { background: #121820; }
.prop-table code { color: var(--signal); }

.grid-2 {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 0;
  border-top: 1px solid var(--hairline);
}
.card-link {
  display: block;
  background: transparent;
  border: 0;
  border-bottom: 1px solid var(--hairline);
  border-right: 1px solid var(--hairline);
  padding: 18px 16px 16px;
  text-decoration: none;
  color: inherit;
}
.card-link:hover {
  background: var(--panel);
  text-decoration: none;
  color: inherit;
}
.card-link .tag {
  font-family: var(--mono);
  font-size: 10px;
  color: var(--playhead);
  letter-spacing: 0.12em;
}
.card-link h3 {
  font-family: var(--display);
  color: var(--ink);
  margin: 6px 0 8px;
  font-size: 1.05rem;
}
.card-link p { color: var(--mute); font-size: 13px; margin: 0; }

.ease-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(170px, 1fr));
  gap: 8px;
  margin-top: 10px;
}
.ease-item {
  padding: 8px 10px;
  background: var(--panel-2);
  border: 1px solid var(--hairline);
  font-family: var(--mono);
  font-size: 11px;
  cursor: pointer;
  text-align: center;
}
.ease-item:hover { border-color: var(--playhead); color: var(--playhead); }

.stagger-row { padding: 28px 20px; }
.stagger-row .box {
  position: relative;
  top: auto;
  left: auto;
  display: inline-flex;
  margin-right: 10px;
}

.menu-btn {
  display: none;
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 40;
}

/* ---------- 页脚：给爬虫的真实内链 ---------- */
.site-footer {
  border-top: 1px solid var(--hairline);
  background: #10151c;
  padding: 36px 40px 48px;
  margin-left: var(--sidebar-w);
}
.site-footer h2 {
  margin: 0 0 16px;
  font-size: 13px;
}
.footer-cols {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
  max-width: 1040px;
}
.footer-cols h3 {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: #6b7382;
  margin: 0 0 10px;
}
.footer-cols a {
  display: block;
  color: var(--mute);
  font-size: 13px;
  padding: 3px 0;
  text-decoration: none;
}
.footer-cols a:hover { color: var(--playhead); }
.footer-note {
  margin-top: 28px;
  font-family: var(--mono);
  font-size: 11px;
  color: #5c6573;
}

@media (max-width: 900px) {
  .sidebar {
    position: fixed;
    z-index: 30;
    transform: translateX(-100%);
    transition: transform 0.25s;
  }
  .sidebar.open { transform: translateX(0); }
  .menu-btn { display: inline-flex; }
  .main { padding: 48px 16px 60px; }
  .time-ruler { margin: 0 -16px 20px; }
  .site-footer { margin-left: 0; padding: 28px 16px 40px; }
  .footer-cols { grid-template-columns: 1fr; }
  .hero-stage { padding: 20px; }
}