:root{--bg:#0e1117;--surface:#161b22;--surface-2:#1c232c;--text:#e6edf3;--text-2:#9da7b3;--text-3:#6b7480;--rule:#242c37;--rule-strong:#323c49;--accent:#7aa2f7;--accent-ink:#a4c0ff;--selection:rgba(122,162,247,0.22);--code-bg:#1a2230;--note-bg:#1d2530;--note-rule:#3a4658}[data-theme=light]{--bg:#fbfbfa;--surface:#ffffff;--surface-2:#f5f5f3;--text:#1a1a1a;--text-2:#4a4a4a;--text-3:#8a8a8a;--rule:#e8e8e4;--rule-strong:#d0d0cc;--accent:#2451b4;--accent-ink:#1a3d8a;--selection:rgba(36,81,180,0.14);--code-bg:#f5f5f3;--note-bg:#faf7ec;--note-rule:#c9b56a}*{margin:0;padding:0;box-sizing:border-box}html{scroll-behavior:smooth}body{font-family:Heebo,'Segoe UI',system-ui,sans-serif;background:var(--bg);color:var(--text);line-height:1.8;font-size:18px;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}::selection{background:var(--selection)}.concepts-layout{display:grid;grid-template-columns:260px 1fr;gap:64px;max-width:100%;margin:0;padding:44px 60px 100px;align-items:start}@media (max-width:1100px){.concepts-layout{padding:36px 32px 80px;gap:48px}}@media (max-width:960px){.concepts-layout{grid-template-columns:1fr;gap:24px;padding:24px 20px 60px}}.concepts-sidebar{position:sticky;top:32px;max-height:calc(100vh - 64px);overflow-y:auto;padding-inline-start:16px;border-inline-start:1px solid var(--rule);font-size:.94rem}@media (max-width:960px){.concepts-sidebar{position:static;border-inline-start:none;border-top:1px solid var(--rule);border-bottom:1px solid var(--rule);padding:14px 0;max-height:none}}.sidebar-heading{font-size:.72rem;font-weight:600;color:var(--text-3);text-transform:uppercase;letter-spacing:.12em;margin-bottom:10px;padding-inline-start:12px}.topic-btn{display:flex;align-items:baseline;justify-content:space-between;width:100%;background:0 0;color:var(--text-2);border:0;padding:7px 12px;font-family:inherit;font-size:.94rem;font-weight:400;cursor:pointer;text-align:start;border-inline-start:2px solid 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