/* ============================================================
   具身智能研习站 · style.css
   主题：机械关节 × 传感器网格 × 运动轨迹
   暗色为默认，亮色通过 [data-theme="light"] 覆盖。
   ============================================================ */

:root {
  --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", "Segoe UI", Roboto, sans-serif;
  --font-serif: "Songti SC", "Noto Serif SC", "STSong", Georgia, "Times New Roman", serif;
  --font-mono: "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  --radius: 12px;
  --radius-sm: 8px;
  --maxw: 1180px;
  --header-h: 58px;
  --tr: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg: #0a0f15;
  --bg-glow-1: rgba(34, 211, 238, 0.08);
  --bg-glow-2: rgba(167, 139, 250, 0.07);
  --grid-line: rgba(148, 178, 205, 0.05);
  --surface: #10171f;
  --surface-2: #141d27;
  --surface-3: #1a2530;
  --line: #1e2a36;
  --line-strong: #2a3947;
  --text: #d9e2ec;
  --text-dim: #8fa0b0;
  --text-faint: #5d6f80;
  --accent: #22d3ee;
  --accent-soft: rgba(34, 211, 238, 0.12);
  --amber: #f5a524;
  --violet: #a78bfa;
  --pink: #f472b6;
  --green: #34d399;
  --blue: #60a5fa;
  --orange: #fb923c;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
  --code-bg: #0d141c;
}

[data-theme="light"] {
  --bg: #f4f7fa;
  --bg-glow-1: rgba(8, 145, 178, 0.07);
  --bg-glow-2: rgba(124, 58, 237, 0.06);
  --grid-line: rgba(30, 64, 90, 0.06);
  --surface: #ffffff;
  --surface-2: #f0f4f8;
  --surface-3: #e6edf3;
  --line: #dde6ee;
  --line-strong: #c3d2df;
  --text: #182430;
  --text-dim: #4d6072;
  --text-faint: #7d90a2;
  --accent: #0891b2;
  --accent-soft: rgba(8, 145, 178, 0.1);
  --amber: #b45309;
  --violet: #7c3aed;
  --pink: #db2777;
  --green: #059669;
  --blue: #2563eb;
  --orange: #ea580c;
  --shadow: 0 8px 24px rgba(23, 48, 71, 0.09);
  --code-bg: #0f1720;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: calc(var(--header-h) + 16px); }
body {
  margin: 0;
  font-family: var(--font-sans);
  background:
    radial-gradient(1000px 500px at 85% -5%, var(--bg-glow-2), transparent 60%),
    radial-gradient(900px 480px at -10% 8%, var(--bg-glow-1), transparent 55%),
    linear-gradient(var(--grid-line) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid-line) 1px, transparent 1px),
    var(--bg);
  background-size: auto, auto, 42px 42px, 42px 42px, auto;
  background-attachment: fixed;
  color: var(--text);
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}
.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 22px; }

::selection { background: var(--accent-soft); color: var(--text); }

a { color: var(--accent); text-decoration: none; transition: color var(--tr); }
a:hover { color: var(--amber); }

.skip {
  position: absolute; left: -9999px; top: 0; z-index: 200;
  background: var(--accent); color: #04222a; padding: 8px 14px; border-radius: 0 0 8px 0; font-weight: 700;
}
.skip:focus { left: 0; }

:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 4px; }

/* ---------------- header ---------------- */

.site-header {
  position: sticky; top: 0; z-index: 100;
  backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px);
  background: color-mix(in srgb, var(--bg) 78%, transparent);
  border-bottom: 1px solid var(--line);
}
.header-inner { display: flex; align-items: center; gap: 18px; height: var(--header-h); }
.brand {
  display: flex; align-items: baseline; gap: 8px; font-family: var(--font-serif);
  font-weight: 800; font-size: 17px; color: var(--text); letter-spacing: 0.5px; white-space: nowrap;
}
.brand:hover { color: var(--accent); }
.brand-mark { color: var(--accent); font-size: 14px; animation: pulse 3s ease-in-out infinite; }
.brand-sub {
  font-size: 10.5px; font-weight: 600; color: var(--text-faint);
  border: 1px solid var(--line-strong); border-radius: 999px; padding: 1px 8px; letter-spacing: 1.5px;
}
@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.45; } }

.site-nav { display: flex; gap: 2px; flex: 1; overflow-x: auto; scrollbar-width: none; }
.site-nav::-webkit-scrollbar { display: none; }
.nav-link {
  color: var(--text-dim); font-size: 13.5px; padding: 6px 11px; border-radius: 8px; white-space: nowrap;
  transition: background var(--tr), color var(--tr);
}
.nav-link:hover { background: var(--surface-2); color: var(--text); }

.header-actions { display: flex; gap: 8px; }
.icon-btn {
  width: 34px; height: 34px; border-radius: 9px; border: 1px solid var(--line);
  background: var(--surface); color: var(--text); font-size: 16px; cursor: pointer;
  display: grid; place-items: center; transition: border-color var(--tr), transform var(--tr);
}
.icon-btn:hover { border-color: var(--accent); transform: translateY(-1px); }

/* ---------------- search ---------------- */

.search-overlay {
  position: fixed; inset: 0; z-index: 150; background: rgba(4, 8, 12, 0.55);
  backdrop-filter: blur(4px); display: flex; justify-content: center; padding-top: 12vh;
}
.search-overlay[hidden] { display: none; }
.search-panel {
  width: min(640px, 92vw); height: fit-content; max-height: 70vh; overflow: auto;
  background: var(--surface); border: 1px solid var(--line-strong); border-radius: 16px;
  box-shadow: var(--shadow); padding: 14px;
}
#search-input {
  width: 100%; padding: 11px 14px; font-size: 15px; border-radius: 10px;
  border: 1px solid var(--line-strong); background: var(--surface-2); color: var(--text); outline: none;
}
#search-input:focus { border-color: var(--accent); }
#search-results { list-style: none; margin: 10px 0 0; padding: 0; }
#search-results li {
  padding: 9px 12px; border-radius: 9px; cursor: pointer; display: flex; gap: 10px; align-items: baseline;
}
#search-results li.active, #search-results li:hover { background: var(--accent-soft); }
#search-results .r-title { font-weight: 600; font-size: 14px; }
#search-results .r-meta { font-size: 11.5px; color: var(--text-faint); margin-left: auto; white-space: nowrap; }
#search-results .r-excerpt { font-size: 12px; color: var(--text-dim); }
.search-hint { font-size: 11.5px; color: var(--text-faint); text-align: center; margin: 10px 0 0; }
kbd {
  font-family: var(--font-mono); font-size: 11px; border: 1px solid var(--line-strong);
  border-bottom-width: 2px; border-radius: 5px; padding: 0 5px; background: var(--surface-2);
}

/* ---------------- hero ---------------- */

.hero { padding: 72px 0 40px; position: relative; overflow: hidden; }
.hero-inner { text-align: center; max-width: 860px; }
.hero-eyebrow {
  font-size: 12px; letter-spacing: 3px; color: var(--accent); font-weight: 700;
  text-transform: uppercase; margin: 0 0 14px;
}
.hero h1 {
  font-family: var(--font-serif); font-size: clamp(40px, 7vw, 62px); line-height: 1.15;
  margin: 0 0 18px; letter-spacing: 2px;
}
.hero-accent {
  background: linear-gradient(100deg, var(--accent), var(--violet) 55%, var(--pink));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero-sub { color: var(--text-dim); font-size: 16.5px; max-width: 660px; margin: 0 auto 26px; }
.hero-actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; margin-bottom: 18px; }

.btn {
  display: inline-block; padding: 11px 22px; border-radius: 11px; font-size: 14.5px; font-weight: 600;
  border: 1px solid var(--line-strong); color: var(--text); background: var(--surface);
  transition: transform var(--tr), border-color var(--tr), box-shadow var(--tr);
}
.btn:hover { transform: translateY(-2px); border-color: var(--accent); box-shadow: var(--shadow); }
.btn-primary {
  background: linear-gradient(120deg, var(--accent), #0ea5b7); color: #03242b; border: none;
}
.btn-primary:hover { color: #03242b; }

.hero-chain { width: min(640px, 92%); margin: 8px auto 0; display: block; }
.chain-lines path { stroke: var(--line-strong); stroke-width: 2.5; stroke-dasharray: 7 6; fill: none; }
.chain-joints circle { fill: var(--surface); stroke: var(--accent); stroke-width: 2.5; }
.chain-joints circle:nth-child(even) { stroke: var(--violet); }
.chain-anim circle { fill: var(--amber); }
.chain-labels text { fill: var(--text-faint); font-size: 12px; text-anchor: middle; font-family: var(--font-sans); }
@media (prefers-reduced-motion: reduce) { .chain-anim circle { display: none; } .brand-mark { animation: none; } }

/* ---------------- shared components ---------------- */

.page-head { padding: 44px 0 10px; }
.page-head h1 { font-family: var(--font-serif); font-size: 34px; margin: 0 0 10px; }
.page-head p { color: var(--text-dim); max-width: 820px; }

.chip {
  display: inline-flex; align-items: center; font-size: 12px; font-weight: 600;
  padding: 3px 10px; border-radius: 999px; border: 1px solid var(--line-strong);
  color: var(--text-dim); background: var(--surface-2);
}
.chip-tag { color: var(--accent); border-color: color-mix(in srgb, var(--accent) 40%, transparent); }
.chip-id { font-family: var(--font-mono); }

.lv-badge { font-size: 11px; font-weight: 700; padding: 1px 8px; border-radius: 999px; }
.lv-basic, .map-node.lv-basic rect { --lv: var(--accent); }
.lv-core, .map-node.lv-core rect { --lv: var(--violet); }
.lv-adv, .map-node.lv-adv rect { --lv: var(--amber); }
.lv-front, .map-node.lv-front rect { --lv: var(--pink); }
.lv-badge.lv-basic { background: color-mix(in srgb, var(--accent) 15%, transparent); color: var(--accent); }
.lv-badge.lv-core { background: color-mix(in srgb, var(--violet) 15%, transparent); color: var(--violet); }
.lv-badge.lv-adv { background: color-mix(in srgb, var(--amber) 15%, transparent); color: var(--amber); }
.lv-badge.lv-front { background: color-mix(in srgb, var(--pink) 18%, transparent); color: var(--pink); }

/* module accent system */
.mod-1 { --mod: var(--accent); }
.mod-2 { --mod: var(--violet); }
.mod-3 { --mod: var(--amber); }
.mod-4 { --mod: var(--pink); }
.mod-5 { --mod: var(--green); }
.mod-6 { --mod: var(--blue); }
.mod-7 { --mod: var(--orange); }

.module-stack { display: grid; gap: 22px; padding-bottom: 64px; }
.module-card {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 22px 24px; position: relative; overflow: hidden;
}
.module-card::before {
  content: ""; position: absolute; inset: 0 auto 0 0; width: 4px;
  background: linear-gradient(var(--mod), transparent);
}
.module-card header { display: flex; align-items: baseline; gap: 14px; flex-wrap: wrap; margin-bottom: 14px; }
.module-card h2 { font-family: var(--font-serif); font-size: 20px; margin: 0; color: var(--mod); }
.module-desc { color: var(--text-faint); font-size: 13px; margin: 0; }

.idx-kp-list, .map-kp-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 8px; }
.idx-kp, .map-kp {
  display: flex; align-items: center; gap: 9px; padding: 9px 12px; border-radius: 9px;
  background: var(--surface-2); border: 1px solid transparent; color: var(--text); font-size: 13.5px;
  transition: border-color var(--tr), transform var(--tr);
}
.idx-kp:hover, .map-kp:hover { border-color: var(--mod); transform: translateX(3px); color: var(--text); }
.idx-kp-id, .map-kp-id { font-family: var(--font-mono); font-size: 11px; color: var(--mod); flex-shrink: 0; }
.idx-kp-title, .map-kp-title { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.map-kp.done .map-kp-title::after { content: " ✓"; color: var(--green); font-weight: 700; }

.feature-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; margin: 34px 0 40px; }
.feature { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 20px; }
.feature h3 { margin: 0 0 8px; font-size: 15.5px; }
.feature p { margin: 0; color: var(--text-dim); font-size: 13.5px; }
.section-title { font-family: var(--font-serif); font-size: 24px; margin: 8px 0 18px; }

/* ---------------- kp layout ---------------- */

.kp-layout { display: grid; grid-template-columns: 210px minmax(0, 1fr); gap: 34px; padding: 36px 22px 60px; }
.kp-side-sticky { position: sticky; top: calc(var(--header-h) + 18px); }
.toc {
  border-left: 2px solid var(--line); padding-left: 14px; margin-bottom: 20px;
  font-size: 12.5px; max-height: 62vh; overflow: auto;
}
.toc-title { color: var(--text-faint); font-weight: 700; letter-spacing: 1px; margin: 0 0 6px; font-size: 11px; }
.toc ol { list-style: none; margin: 0; padding: 0; }
.toc a { color: var(--text-dim); display: block; padding: 3.5px 0; border-radius: 4px; }
.toc a:hover { color: var(--mod, var(--accent)); }
.toc a.active { color: var(--mod, var(--accent)); font-weight: 700; }

.progress-toggle { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--text-dim); cursor: pointer; user-select: none; }
.progress-toggle input { accent-color: var(--green); width: 16px; height: 16px; cursor: pointer; }
.progress-hint { font-size: 11.5px; color: var(--text-faint); margin: 6px 0 0; }

.progress-bar { height: 6px; border-radius: 999px; background: var(--surface-3); overflow: hidden; max-width: 340px; margin: 8px auto 4px; }
.progress-bar > i { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--accent), var(--green)); transition: width 0.5s ease; }
[data-progress-summary] { font-size: 12px; color: var(--text-faint); }

.crumbs { font-size: 12.5px; color: var(--text-faint); margin-bottom: 14px; display: flex; gap: 8px; flex-wrap: wrap; }
.kp-title { font-family: var(--font-serif); font-size: clamp(26px, 4vw, 36px); margin: 0 0 14px; line-height: 1.3; }
.kp-meta { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 26px; }
.kp-article { min-width: 0; }

.kp-body { font-size: 15.5px; }
.kp-body h2 {
  font-family: var(--font-serif); font-size: 21px; margin: 40px 0 12px; padding-top: 14px;
  border-top: 1px dashed var(--line);
}
.kp-body h2:first-child { border-top: none; margin-top: 0; padding-top: 0; }
.kp-body h3 { font-size: 16.5px; margin: 26px 0 8px; }
.kp-body p { margin: 0 0 14px; color: var(--text); }
.kp-body ul, .kp-body ol { padding-left: 22px; margin: 0 0 14px; }
.kp-body li { margin-bottom: 6px; }
.kp-body li::marker { color: var(--mod, var(--accent)); }

.kp-body code {
  font-family: var(--font-mono); font-size: 0.86em; background: var(--surface-3);
  padding: 2px 6px; border-radius: 5px; color: var(--accent);
}
.kp-body pre {
  background: var(--code-bg); border: 1px solid var(--line); border-radius: var(--radius-sm);
  padding: 16px 18px; overflow-x: auto; margin: 0 0 16px;
}
.kp-body pre code { background: none; padding: 0; color: #b8cadb; font-size: 13px; line-height: 1.6; }

.kp-body blockquote {
  margin: 0 0 16px; padding: 10px 18px; border-left: 3px solid var(--mod, var(--accent));
  background: var(--surface-2); border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--text-dim);
}
.kp-body hr { border: none; border-top: 1px solid var(--line); margin: 30px 0; }

.table-wrap { overflow-x: auto; margin: 0 0 18px; border: 1px solid var(--line); border-radius: var(--radius-sm); }
.kp-body table, .doc-body table { border-collapse: collapse; width: 100%; font-size: 13.5px; }
.kp-body th, .kp-body td, .doc-body th, .doc-body td {
  text-align: left; padding: 9px 13px; border-bottom: 1px solid var(--line); vertical-align: top;
}
.kp-body th, .doc-body th { background: var(--surface-2); color: var(--mod, var(--accent)); font-size: 12.5px; white-space: nowrap; }
.kp-body tr:last-child td, .doc-body tr:last-child td { border-bottom: none; }
.kp-body tbody tr:hover td { background: color-mix(in srgb, var(--mod, var(--accent)) 5%, transparent); }

.math-display {
  overflow-x: auto; padding: 14px 10px; margin: 0 0 16px; text-align: center;
  background: var(--surface-2); border-radius: var(--radius-sm); border: 1px dashed var(--line);
}
.math-inline { color: var(--text); white-space: nowrap; }

/* reveal animation（仅在 JS 可用时启用，禁 JS 时内容直接可见） */
.js .kp-body > *, .js .doc-body > * { opacity: 0; transform: translateY(10px); transition: opacity 0.5s ease, transform 0.5s ease; }
.js .kp-body > *.visible, .js .doc-body > *.visible, .no-reveal .kp-body > *, .no-reveal .doc-body > * { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) { .js .kp-body > *, .js .doc-body > * { opacity: 1; transform: none; transition: none; } }

.kp-extra { margin-top: 34px; display: grid; gap: 22px; }
.extra-block h2 { font-size: 14px; letter-spacing: 1px; color: var(--text-faint); margin: 0 0 10px; }
.sources { font-size: 13px; color: var(--text-dim); padding-left: 20px; margin: 0; }
.related-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 10px; }
.related-card {
  display: flex; flex-direction: column; gap: 3px; padding: 12px 14px; border-radius: 10px;
  background: var(--surface-2); border: 1px solid var(--line); color: var(--text); font-size: 13.5px;
  border-left: 3px solid var(--mod);
}
.related-card:hover { border-color: var(--mod); color: var(--text); }
.related-id { font-family: var(--font-mono); font-size: 11px; color: var(--mod); }

.pn-nav { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; margin-top: 38px; }
.pn-card {
  display: flex; flex-direction: column; gap: 4px; padding: 15px 18px; border-radius: var(--radius);
  border: 1px solid var(--line); background: var(--surface); color: var(--text);
  transition: border-color var(--tr), transform var(--tr);
}
.pn-card:hover { border-color: var(--accent); transform: translateY(-2px); color: var(--text); }
.pn-next { text-align: right; }
.pn-label { font-size: 11.5px; color: var(--text-faint); }
.pn-title { font-weight: 700; font-size: 14.5px; }
.pn-empty { visibility: hidden; }

/* ---------------- map page ---------------- */

.map-scroll { overflow-x: auto; padding: 16px 0 8px; margin-bottom: 18px; }
.map-edge { fill: none; stroke: var(--line-strong); stroke-width: 1.4; opacity: 0.55; }
.map-node rect {
  fill: var(--surface-2); stroke: color-mix(in srgb, var(--lv, var(--accent)) 55%, transparent);
  stroke-width: 1.4; transition: fill 0.2s ease;
}
.map-node:hover rect { fill: var(--surface-3); }
.map-node.done rect { stroke: var(--green); stroke-width: 2; }
.map-node-id { fill: var(--lv, var(--accent)); font-size: 10px; font-family: var(--font-mono); }
.map-node-title { fill: var(--text); font-size: 13px; font-weight: 600; }
.map-mod-label { font-size: 14px; font-weight: 800; font-family: var(--font-serif); }
.done-dot { display: inline-block; width: 9px; height: 9px; border-radius: 50%; background: var(--green); margin: 0 3px; }

/* ---------------- doc pages ---------------- */

.doc-body { max-width: 860px; padding-bottom: 60px; font-size: 15px; }
.doc-body h2 { font-family: var(--font-serif); border-top: 1px dashed var(--line); padding-top: 16px; margin-top: 30px; }
.doc-body h3 { margin: 22px 0 8px; }

/* ---------------- footer ---------------- */

.site-footer { border-top: 1px solid var(--line); margin-top: 30px; padding: 26px 0 34px; }
.footer-inner { color: var(--text-faint); font-size: 12.5px; text-align: center; }
.footer-links { margin-top: 6px; }

/* ---------------- responsive ---------------- */

@media (max-width: 900px) {
  .kp-layout { grid-template-columns: 1fr; gap: 10px; }
  .kp-side { order: 2; }
  .kp-side-sticky { position: static; }
  .toc { max-height: none; columns: 2; column-gap: 24px; border-left: none; padding-left: 0; }
  .toc a { display: inline-block; padding: 3px 10px 3px 0; }
  .brand-sub { display: none; }
}
@media (max-width: 640px) {
  .hero { padding-top: 48px; }
  .site-nav { gap: 0; }
  .nav-link { padding: 6px 8px; font-size: 12.5px; }
  .pn-nav { grid-template-columns: 1fr; }
  .pn-next { text-align: left; }
  .toc { columns: 1; }
  .wrap { padding: 0 14px; }
}

/* ---------------- print ---------------- */
@media print {
  .site-header, .site-footer, .search-overlay, .kp-side, .pn-nav, .hero-actions { display: none !important; }
  body { background: #fff; color: #111; }
  .kp-body > * { opacity: 1 !important; transform: none !important; }
}