:root{
    --bg:#ffffff;--ink:#0a0a0a;--ink-2:#3d3d3d;--ink-3:#8a8a8a;
    --line:#e6e6e6;--line-2:#d2d2d2;--paper:#fafafa;
    --black:#0c0c0d;--code-bg:#f6f6f4;
    --signal:#1d4ed8;--signal-soft:#eef2ff;
    --term-green:#4ec9a8;--term-blue:#6aa0ff;
    --sidebar:266px;--toc:208px;
  }
  *{box-sizing:border-box;margin:0;padding:0}
  html{scroll-behavior:smooth;scrollbar-gutter:stable}

  /* ── Anti-FOUC ──────────────────────────────────────────────────────────
     Each doc ships as a bare <article>; site.js builds the header + sidebar +
     TOC grid at runtime (see mount()). Without this, the browser paints the
     raw article at full width with no sidebar for a beat before the script
     runs — a wide flash on every navigation, and a "content but no nav" frame
     on slow loads. Hide the article until mount() adds body.ready, then fade
     the assembled layout in. The keyframe is a safety net: if the script never
     runs, content still appears after 2s instead of staying blank forever. */
  body:not(.ready) article{visibility:hidden}
  article{animation:doc-fouc-guard .001s linear 2s forwards}
  @keyframes doc-fouc-guard{to{visibility:visible}}
  body.ready .layout{animation:doc-reveal .2s ease both}
  @keyframes doc-reveal{from{opacity:0}to{opacity:1}}
  body{
    background:var(--bg);color:var(--ink);
    font-family:'JetBrains Mono',ui-monospace,SFMono-Regular,Menlo,monospace;
    font-size:14px;line-height:1.7;-webkit-font-smoothing:antialiased;
  }
  a{color:inherit;text-decoration:none}
  ::selection{background:#cfe1ff;color:#0a0a0a}
  .code ::selection,.code pre::selection{background:#33467c;color:#fff}
  code{font-family:inherit}

  /* header */
  header{position:sticky;top:0;z-index:60;background:rgba(255,255,255,.9);backdrop-filter:saturate(180%) blur(10px);border-bottom:1px solid var(--line)}
  .nav{display:flex;align-items:center;gap:22px;height:60px;padding:0 24px}
  .brand{font-family:'JetBrains Mono',ui-monospace,SFMono-Regular,Menlo,monospace;font-weight:700;font-size:16px;display:flex;align-items:center;gap:8px;letter-spacing:-.2px}
  .brand .brand-logo{height:44px;width:auto;display:block}
  .nav .spacer{flex:1}
  .nav nav{display:flex;gap:20px;font-size:13px;align-items:center}
  .nav nav a{color:var(--ink-2)}
  .nav nav a:hover{color:var(--ink)}
  .lang-toggle{
    display:inline-flex;align-items:center;position:relative;
    border:1px solid var(--line-2);border-radius:999px;background:var(--paper);
    padding:2px;font-size:12px;line-height:1;user-select:none;overflow:hidden;
  }
  .lang-toggle .seg{
    position:relative;z-index:1;display:inline-flex;align-items:center;justify-content:center;
    width:38px;padding:4px 0;border-radius:999px;color:var(--ink-3)!important;
    letter-spacing:.3px;transition:color .25s ease;
  }
  .lang-toggle .seg.on{color:var(--bg)!important;font-weight:600}
  .lang-toggle .thumb{
    position:absolute;top:2px;bottom:2px;z-index:0;border-radius:999px;background:var(--ink);
    transition:transform .28s cubic-bezier(.4,0,.2,1),width .28s cubic-bezier(.4,0,.2,1);
  }
  .lang-toggle:hover{border-color:var(--ink)}
  .search-wrap{position:relative;display:inline-flex;align-items:center}
  .search-ico{position:absolute;left:11px;width:14px;height:14px;pointer-events:none;fill:none;stroke:var(--ink-3);stroke-width:1.6;stroke-linecap:round;transition:stroke .15s}
  .search{border:1px solid var(--line-2);border-radius:999px;background:var(--paper);padding:7px 14px 7px 32px;font:inherit;font-size:12.5px;line-height:1;color:var(--ink);width:172px;transition:border-color .15s,background .15s,box-shadow .15s}
  .search::placeholder{color:var(--ink-3)}
  .search:hover{border-color:var(--ink-3)}
  .search:focus{outline:none;border-color:var(--signal);background:var(--bg);box-shadow:0 0 0 3px var(--signal-soft)}
  .search-wrap:focus-within .search-ico{stroke:var(--signal)}
  .sb-toggle{display:none;background:none;border:1px solid var(--line-2);padding:6px 9px;font:inherit;cursor:pointer}

  /* layout */
  .layout{display:grid;grid-template-columns:var(--sidebar) minmax(0,1fr) var(--toc);max-width:1340px;margin:0 auto;align-items:start}

  /* sidebar */
  .sidebar{position:sticky;top:60px;height:calc(100vh - 60px);overflow-y:auto;border-right:1px solid var(--line);padding:30px 22px 60px}
  .sidebar .group{margin-bottom:26px}
  .sidebar .group > .lbl{font-size:11px;text-transform:uppercase;letter-spacing:1px;color:var(--ink-3);margin-bottom:10px;font-weight:700}
  .sidebar a{display:block;color:var(--ink-2);font-size:13px;padding:5px 10px;border-left:2px solid transparent;transition:.13s}
  .sidebar a:hover{color:var(--ink);background:var(--paper)}
  .sidebar a.active{color:var(--ink);border-left-color:var(--signal);font-weight:500;background:var(--paper)}

  /* content */
  main{padding:46px 56px 120px;min-width:0}
  .crumb{font-size:12px;color:var(--ink-3);margin-bottom:26px}
  .crumb a:hover{color:var(--ink)}
  .crumb span{color:var(--ink)}
  article h1{font-size:34px;letter-spacing:-1px;margin-bottom:14px;font-weight:700;line-height:1.1}
  article h1::before{content:"";display:inline-block;width:11px;height:11px;background:var(--signal);margin-right:13px;vertical-align:middle;transform:translateY(-3px)}
  article .tagline{color:var(--ink-2);font-size:15px;margin-bottom:42px;padding-bottom:22px;border-bottom:1px solid var(--line);text-align:left}
  /* screenshot figure — page intro shot */
  figure.shot{margin:0 0 42px}
  figure.shot img{display:block;width:100%;height:auto;border:1px solid var(--line-2);border-radius:7px}
  figure.shot figcaption{margin-top:9px;font-size:12px;color:var(--ink-3);text-align:center}
  figure.shot img{cursor:zoom-in}

  /* feature demos — poster-first; the video element is created only on click */
  figure.feature-demo{margin:0 0 42px}
  figure.feature-demo video,
  figure.feature-demo .feature-demo-trigger{
    display:block;width:100%;height:auto;aspect-ratio:960/594;object-fit:cover;
    border:1px solid var(--line-2);border-radius:7px;background:#111;
  }
  figure.feature-demo .feature-demo-trigger{position:relative;padding:0;overflow:hidden;cursor:pointer;appearance:none;font:inherit;color:inherit}
  figure.feature-demo .feature-demo-trigger img{display:block;width:100%;height:100%;object-fit:cover}
  figure.feature-demo .feature-demo-trigger::before{
    content:"";position:absolute;left:50%;top:50%;width:54px;height:54px;
    transform:translate(-50%,-50%);border-radius:50%;background:rgba(0,0,0,.58);
    box-shadow:0 8px 28px rgba(0,0,0,.24);transition:background .15s,transform .15s;
  }
  figure.feature-demo .feature-demo-trigger::after{
    content:"";position:absolute;left:50%;top:50%;transform:translate(-38%,-50%);
    border-left:16px solid #fff;border-top:11px solid transparent;border-bottom:11px solid transparent;
  }
  figure.feature-demo .feature-demo-trigger:hover::before{background:rgba(0,0,0,.72);transform:translate(-50%,-50%) scale(1.05)}
  figure.feature-demo figcaption{margin-top:9px;font-size:12px;color:var(--ink-3);text-align:center}
  .feature-demo-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:18px;margin:20px 0 28px}
  .feature-demo-grid figure.feature-demo{margin:0}
  .feature-demo-grid figure.feature-demo figcaption{text-align:left;line-height:1.45}

  /* introduction diagrams — crisp inline-SVG schematics (one visual language) */
  .intro-diagram{margin:22px 0 28px;border:1px solid var(--line-2);border-radius:10px;background:#fff;overflow:hidden}
  .intro-diagram .dg-head{padding:12px 16px 0}
  .intro-viz-title{font-size:11px;text-transform:uppercase;letter-spacing:1px;color:var(--ink-3);font-weight:700}
  .intro-diagram .dg-canvas{padding:8px 16px 14px;overflow-x:auto}
  .intro-diagram figcaption{padding:11px 16px;border-top:1px solid var(--line);font-size:12px;color:var(--ink-3);line-height:1.55;text-align:left}
  /* shared SVG drawing vocabulary */
  .dg{display:block;width:100%;height:auto}
  .dg text{font-family:'JetBrains Mono',ui-monospace,SFMono-Regular,Menlo,monospace}
  .dg .t-title{fill:var(--ink);font-weight:700;font-size:13.5px}
  .dg .t-sub{fill:var(--ink-2);font-size:10.5px;letter-spacing:-.1px}
  .dg .t-chip{fill:var(--ink-3);font-size:11px}
  .dg .t-num{fill:#fff;font-weight:700;font-size:11px}
  .dg .t-cap{fill:var(--ink);font-weight:700;font-size:13px}
  .dg .t-flow{fill:var(--ink-3);font-size:10.5px;letter-spacing:.3px}
  .dg .t-flow.em{fill:var(--ink-2);font-weight:700}
  .dg .nd{stroke-width:1.5}
  .dg .num-bg{fill:var(--ink)}
  .dg .edge{stroke:var(--ink-3);stroke-width:1.6;fill:none}
  .dg .edge.dash{stroke-dasharray:5 4}
  .dg .edge.loop{stroke:#2563eb;stroke-width:1.6;stroke-dasharray:6 4}
  .dg .n-robot{fill:#f5faf6;stroke:#2f9e44}
  .dg .n-eva{fill:#f4f8ff;stroke:#2563eb}
  .dg .n-policy{fill:#fdf6f2;stroke:#c2410c}
  .dg .s-manual{fill:#f4faf5;stroke:#2f9e44}
  .dg .s-collect{fill:#fbf8ed;stroke:#a16207}
  .dg .s-train{fill:#fdf4ee;stroke:#c2410c;stroke-dasharray:5 4}
  .dg .s-debug{fill:#f3f7ff;stroke:#2563eb}
  .dg .s-eval{fill:#fdf1f4;stroke:#be123c}
  .dg .s-result{fill:#f8f5fd;stroke:#6f42c1}
  .dg .b-green{fill:#f5faf6;stroke:#2f9e44}
  .dg .b-orange{fill:#fdf6f2;stroke:#c2410c}
  .dg .b-blue{fill:#f4f8ff;stroke:#2563eb}
  .dg .b-purple{fill:#f8f5fd;stroke:#6f42c1}
  .dg .cap-box{fill:#fff;stroke:var(--ink);stroke-width:1.6}

  /* live 3D viewer (replaces the old static screenshot) */
  .intro-3d{position:relative;margin:22px 0 30px;border:1px solid var(--line-2);border-radius:10px;background:#fff;overflow:hidden}
  .intro-3d .r3d-stage{position:relative;width:100%;aspect-ratio:16/10;background:linear-gradient(180deg,#fff,#f6f7f8)}
  .intro-3d canvas{display:block;width:100%;height:100%;touch-action:none}
  .intro-3d .r3d-tag{position:absolute;top:12px;left:14px;z-index:2;font-size:10.5px;letter-spacing:1px;text-transform:uppercase;color:var(--ink-3);background:rgba(255,255,255,.82);border:1px solid var(--line-2);border-radius:999px;padding:3px 10px;backdrop-filter:blur(4px)}
  .intro-3d .r3d-hint{position:absolute;bottom:12px;right:14px;z-index:2;font-size:11px;color:var(--ink-3);background:rgba(255,255,255,.82);border:1px solid var(--line);border-radius:6px;padding:4px 9px;backdrop-filter:blur(4px);opacity:0;transition:opacity .4s ease}
  .intro-3d.r3d-ready .r3d-hint{opacity:1}
  .intro-3d .r3d-status{position:absolute;inset:0;z-index:1;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:8px;color:var(--ink-3);font-size:12px;text-align:center;padding:20px}
  .intro-3d .r3d-status .r3d-spin{width:26px;height:26px;border:2px solid var(--line-2);border-top-color:var(--ink);border-radius:50%;animation:r3dspin .8s linear infinite}
  .intro-3d.r3d-ready .r3d-status{display:none}
  .intro-3d .r3d-status[data-kind="error"] .r3d-spin{display:none}
  @keyframes r3dspin{to{transform:rotate(360deg)}}
  .intro-3d figcaption{padding:11px 16px;border-top:1px solid var(--line);font-size:12px;color:var(--ink-3);line-height:1.55;text-align:left}

  .intro-shot-grid{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:12px;margin:20px 0 28px}
  .intro-shot-grid figure.shot{margin:0}
  .intro-shot-grid figure.shot img{aspect-ratio:16/10;object-fit:cover;object-position:top left;border-radius:6px}
  .intro-shot-grid figure.shot figcaption{font-size:11px;line-height:1.4;text-align:left}
  /* click-to-zoom lightbox for doc screenshots */
  #imglb{position:fixed;inset:0;z-index:1000;display:none;align-items:center;justify-content:center;padding:4vw;background:rgba(8,8,10,.9);cursor:zoom-out}
  #imglb.show{display:flex}
  #imglb img{max-width:100%;max-height:88vh;border-radius:8px;box-shadow:0 24px 60px -20px rgba(0,0,0,.6);cursor:default}
  #imglb figcaption{position:absolute;left:0;right:0;bottom:18px;text-align:center;color:#e8e8ea;font-size:13px;letter-spacing:.2px;padding:0 4vw}
  #imglb-close{position:absolute;top:18px;right:22px;width:40px;height:40px;border:0;border-radius:50%;background:rgba(255,255,255,.12);color:#fff;font-size:20px;line-height:1;cursor:pointer;transition:background .15s,transform .12s}
  #imglb-close:hover{background:rgba(255,255,255,.22)}
  #imglb-close:active{transform:scale(.9)}
  article section{margin-bottom:52px;scroll-margin-top:80px}
  article h2{font-size:21px;letter-spacing:-.4px;margin-bottom:16px;padding-top:6px;font-weight:700}
  article h2::before{content:"# ";color:var(--signal)}
  article h3{font-size:15.5px;margin:26px 0 10px;font-weight:700;padding-left:11px;border-left:3px solid var(--signal)}
  article p{color:var(--ink-2);margin-bottom:14px;text-align:left}
  article p b,article li b{color:var(--ink);font-weight:700}
  article ul{margin:0 0 16px 0;padding-left:22px;color:var(--ink-2);list-style:none}
  article li{position:relative;margin-bottom:8px;text-align:left}
  article ul>li::before{content:"";position:absolute;left:-18px;top:.62em;width:5px;height:5px;background:var(--signal)}
  /* keep technical strings whole even under justification */
  article p code,article li code{hyphens:none}
  article p code,article li code,article td code{background:var(--code-bg);border:1px solid var(--line);padding:1px 6px;font-size:12.5px;color:var(--ink);white-space:nowrap}
  article a.ln{color:var(--ink);border-bottom:1px solid var(--signal);transition:background .12s}
  article a.ln:hover{background:var(--signal-soft)}
  .note{border:1px solid var(--line-2);border-left:3px solid var(--signal);background:var(--signal-soft);padding:14px 18px;margin:18px 0;font-size:13px;color:var(--ink-2)}
  .note b{color:var(--ink)}

  /* code block */
  .code{background:#1a1b26;border-radius:8px;overflow:hidden;margin:18px 0;border:1px solid #2a2c3d;box-shadow:0 10px 30px -18px rgba(0,0,0,.6)}
  .code .bar{display:flex;align-items:center;gap:7px;padding:9px 14px;border-bottom:1px solid #2a2c3d;background:#16161e}
  .code .bar .d{width:10px;height:10px;border-radius:50%}
  .code .bar .r{background:#ff5f57}.code .bar .y{background:#febc2e}.code .bar .g{background:#28c840}
  .code .bar .lang{margin-left:8px;font-size:11px;color:#565f89}
  .code .bar .cp{margin-left:auto;background:none;border:1px solid #2f3245;color:#7982a9;cursor:pointer;font:inherit;font-size:11px;padding:3px 9px;border-radius:5px;transition:border-color .15s,color .15s}
  .code .bar .cp:hover{border-color:#7aa2f7;color:#c0caf5}
  .code pre{padding:16px 18px;overflow-x:auto;font-size:12.8px;line-height:1.75;color:#c0caf5}
  /* syntax theme — Tokyo Night-inspired, 8 token classes */
  .code pre .cm{color:#5b6385;font-style:italic}   /* comment */
  .code pre .kw{color:#bb9af7}                       /* keyword: def/class/return/import/if */
  .code pre .dec{color:#7aa2f7;font-style:italic}    /* decorator: @ROBOT_REGISTRY.register */
  .code pre .nm{color:#7dcfff}                        /* assignment target / config section name */
  .code pre .bi{color:#7aa2f7}                        /* builtin / type / call: dict, Path, np */
  .code pre .gr{color:#9ece6a}                        /* string */
  .code pre .nu{color:#ff9e64}                        /* number: 9000, 3.0 */
  .code pre .cn{color:#ff9e64;font-weight:600}        /* constant: True/False/None */
  .code pre .fl{color:#e0af68}                        /* CLI flag: --config, -e */
  /* legacy aliases kept so any un-migrated span still colors sensibly */
  .code pre .bl{color:#bb9af7}.code pre .ky{color:#7aa2f7}

  /* table */
  .tbl-wrap{margin:18px 0;max-width:100%;overflow-x:auto}    /* safety net: a too-wide table scrolls inside the content column instead of overflowing the TOC */
  .tbl{border:1px solid var(--line);font-size:13px;width:100%;border-collapse:collapse;table-layout:auto}
  .tbl-wrap .tbl{margin:0}
  .tbl th{text-align:left;background:var(--paper);padding:10px 14px;border-bottom:1px solid var(--line);border-right:1px solid var(--line);font-weight:700;font-size:12px}
  .tbl td{padding:10px 14px;border-bottom:1px solid var(--line);border-right:1px solid var(--line);color:var(--ink-2);vertical-align:top}
  .tbl th:last-child,.tbl td:last-child{border-right:none}
  .tbl tr:last-child td{border-bottom:none}
  /* columns size to their content (longest cell drives width). Code chips wrap only
     at existing spaces/commas — never mid-token — so a multi-token cell folds onto
     more lines instead of forcing the column wide, while identifiers stay intact. */
  .tbl td code,.tbl th code{white-space:normal;overflow-wrap:normal;word-break:normal}

  /* prev/next */
  .pn{display:flex;justify-content:space-between;gap:16px;margin-top:60px;padding-top:28px;border-top:1px solid var(--line)}
  .pn a{flex:1;border:1px solid var(--line);padding:16px 18px;transition:.15s}
  .pn a:hover{border-color:var(--ink);background:var(--paper)}
  .pn .dir{font-size:11px;color:var(--ink-3);text-transform:uppercase;letter-spacing:1px;margin-bottom:5px}
  .pn .ttl{font-size:14px;color:var(--ink);font-weight:500}
  .pn .next{text-align:right}
  .pn .placeholder{flex:1}

  /* TOC */
  .toc{position:sticky;top:60px;height:calc(100vh - 60px);overflow-y:auto;padding:46px 20px 60px;border-left:1px solid var(--line)}
  .toc .lbl{font-size:11px;text-transform:uppercase;letter-spacing:1px;color:var(--ink-3);margin-bottom:12px;font-weight:700}
  .toc a{display:block;font-size:12px;color:var(--ink-3);padding:4px 0 4px 12px;border-left:2px solid var(--line);transition:.13s}
  .toc a:hover{color:var(--ink-2)}
  .toc a.active{color:var(--ink);border-left-color:var(--signal)}

  .overlay{display:none}
  @media(max-width:1140px){
    .layout{grid-template-columns:var(--sidebar) minmax(0,1fr)}
    .toc{display:none}
  }
  @media(max-width:860px){
    .nav nav{display:none}
    .search{width:110px}
    .sb-toggle{display:inline-block}
    .layout{grid-template-columns:1fr}
    .sidebar{position:fixed;top:60px;left:0;bottom:0;width:280px;background:var(--bg);z-index:55;transform:translateX(-100%);transition:transform .22s;border-right:1px solid var(--line-2)}
    .sidebar.open{transform:none}
    .overlay.show{display:block;position:fixed;inset:60px 0 0 0;background:rgba(0,0,0,.3);z-index:54}
    main{padding:34px 22px 90px}
    .feature-demo-grid{grid-template-columns:1fr}
    .intro-shot-grid{grid-template-columns:1fr 1fr}
  }
  @media(max-width:520px){
    .intro-shot-grid{grid-template-columns:1fr}
  }