.chapter-page main { overflow: visible; }
.chapter-links .is-current { color: var(--accent); border-color: var(--accent); background: var(--bg-soft); }

.chapter-hero,.chapter-section,.chapter-pagination { width:min(var(--max),calc(100% - 2rem)); margin-inline:auto; }
.chapter-hero { padding:clamp(2rem,5vw,4.5rem) 0 clamp(3rem,7vw,6rem); }
.chapter-kicker { display:flex; flex-wrap:wrap; gap:.55rem; align-items:center; margin-bottom:1.5rem; color:var(--muted); font-size:.78rem; }
.chapter-kicker a { color:var(--muted); text-decoration:none; }
.chapter-kicker a:hover { color:var(--accent); }
.chapter-kicker strong { color:var(--accent); }
.chapter-hero-grid { display:grid; grid-template-columns:.8fr 1.2fr; align-items:center; gap:clamp(2rem,5vw,5rem); }
.chapter-hero h1 { margin:0; font-size:clamp(3.2rem,7vw,7rem); line-height:.9; letter-spacing:-.055em; }
.chapter-hero h1 span { color:var(--accent); }
.chapter-lede { max-width:680px; margin:1.4rem 0 0; color:var(--muted); font-size:clamp(1rem,1.3vw,1.16rem); }
.assumption-row { display:flex; flex-wrap:wrap; gap:.45rem; margin-top:1.5rem; }
.assumption-row span { padding:.45rem .65rem; border:1px solid var(--line); border-radius:999px; color:var(--muted); background:var(--panel); font:700 .7rem ui-monospace,monospace; }
.chapter-concept { margin:0; padding:.65rem; border:1px solid var(--line); border-radius:22px; background:var(--panel); box-shadow:0 24px 60px var(--shadow); }
.chapter-concept img { width:100%; border-radius:16px; }

.chapter-section { padding:clamp(3.5rem,7vw,6.5rem) 0; border-top:1px solid var(--line); }
.concept-grid,.insight-grid { display:grid; grid-template-columns:repeat(3,1fr); gap:1rem; margin-top:2rem; }
.concept-card,.insight-grid article { padding:1.1rem; border:1px solid var(--line); border-radius:var(--radius); background:var(--panel); }
.concept-card h3,.insight-grid h3 { margin:.45rem 0 .6rem; }
.concept-card p,.insight-grid p { margin:.55rem 0 0; color:var(--muted); font-size:.9rem; }
.formula { padding:.75rem .85rem; border:1px solid var(--line); border-radius:10px; background:var(--bg-soft); color:var(--accent); font:700 .92rem ui-monospace,monospace; }

.lab-shell { display:grid; grid-template-columns:minmax(0,1fr) 300px; gap:1rem; margin-top:2rem; }
.lab-main,.control-panel { border:1px solid var(--line); border-radius:var(--radius); background:var(--panel); }
.lab-main { min-width:0; overflow:hidden; }
.lab-toolbar { display:flex; justify-content:space-between; align-items:center; gap:1rem; padding:.8rem 1rem; border-bottom:1px solid var(--line); }
.lab-toolbar-title { display:grid; grid-template-columns:auto 1fr; column-gap:.55rem; align-items:center; }
.lab-toolbar-title .status-dot { grid-row:1/3; }
.lab-toolbar-title small { color:var(--muted); font-size:.68rem; }
.status-dot { width:9px; height:9px; border-radius:50%; background:var(--accent); box-shadow:0 0 0 4px color-mix(in srgb,var(--accent) 15%,transparent); }
.lab-actions { display:flex; gap:.45rem; }
.lab-button { min-height:36px; padding:.45rem .7rem; border:1px solid var(--line); border-radius:9px; background:var(--bg-soft); color:var(--text); font:inherit; font-size:.76rem; font-weight:750; cursor:pointer; }
.lab-button:hover { border-color:var(--line-strong); }
.lab-button:focus-visible { outline:2px solid var(--accent); outline-offset:2px; }

.observation-grid { display:grid; grid-template-columns:1fr 1fr; gap:.65rem; padding:.75rem; }
.plot-card { min-width:0; border:1px solid var(--line); border-radius:14px; background:var(--nav-bg); overflow:hidden; }
.plot-card header { display:flex; justify-content:space-between; align-items:center; gap:1rem; padding:.6rem .75rem; border-bottom:1px solid var(--line); }
.plot-card header strong { font-size:.78rem; }
.plot-card header span { color:var(--muted); font-size:.65rem; }
.plot-card svg { width:100%; height:auto; display:block; }
.plot-bg { fill:var(--nav-bg); }
.grid-line { stroke:var(--line); stroke-width:1; opacity:.75; }
.axis-line { stroke:var(--line-strong); stroke-width:1.2; }
.axis-text { fill:var(--muted); font-family:ui-monospace,monospace; font-size:10px; }
.truth-path { fill:none; stroke:var(--accent); stroke-width:3.2; }
.estimate-path { fill:none; stroke:var(--accent-2); stroke-width:2.6; }
.measurement-point { fill:var(--muted); opacity:.48; }
.sensor-marker { fill:var(--danger); stroke:var(--nav-bg); stroke-width:2; }
.measurement-marker { fill:var(--muted); stroke:var(--nav-bg); stroke-width:2; }
.estimate-marker { fill:var(--accent-2); stroke:var(--nav-bg); stroke-width:2; }
.error-path { fill:none; stroke:var(--danger); stroke-width:2.5; }
.sigma-path { fill:none; stroke:var(--accent-2); stroke-width:2; stroke-dasharray:7 6; }
.time-cursor { stroke:var(--accent); stroke-width:2; stroke-dasharray:5 5; }

.timeline-control { padding:.2rem 1rem .85rem; }
.timeline-control label { display:flex; justify-content:space-between; gap:1rem; color:var(--muted); font-size:.75rem; margin-bottom:.45rem; }
.timeline-control output { color:var(--text); font-variant-numeric:tabular-nums; }
.timeline-control input,.control input[type="range"] { width:100%; accent-color:var(--accent); }

.lab-legend { display:flex; flex-wrap:wrap; gap:.75rem 1rem; padding:.75rem 1rem 1rem; color:var(--muted); font-size:.7rem; }
.lab-legend span { display:inline-flex; align-items:center; gap:.42rem; }
.legend-line { width:24px; height:0; border-top:3px solid var(--accent); }
.legend-line.estimate { border-color:var(--accent-2); }
.legend-line.sigma { border-top:2px dashed var(--accent-2); }
.legend-dot { width:8px; height:8px; border-radius:50%; }
.legend-dot.measure { background:var(--muted); }
.legend-dot.sensor { background:var(--danger); }

.transfer-status { margin:0 1rem 1rem; padding:.7rem .8rem; border:1px solid var(--line); border-radius:10px; background:var(--bg-soft); color:var(--muted); font-size:.72rem; }
.transfer-status strong { color:var(--accent); margin-right:.35rem; }

.control-panel { padding:1rem; }
.control-head h3 { margin:-.25rem 0 1rem; }
.control { padding:.8rem 0; border-top:1px solid var(--line); }
.control label { display:flex; justify-content:space-between; gap:.75rem; margin-bottom:.55rem; color:var(--muted); font-size:.75rem; }
.control output { color:var(--text); font-weight:750; font-variant-numeric:tabular-nums; }
.control-note { margin-top:.8rem; padding:.8rem; border:1px solid var(--line); border-radius:10px; background:var(--bg-soft); }
.control-note strong { font-size:.76rem; color:var(--accent-2); }
.control-note p { margin:.35rem 0 0; color:var(--muted); font-size:.72rem; }

.metric-grid { display:grid; grid-template-columns:repeat(auto-fit,minmax(135px,1fr)); gap:.65rem; margin-top:.7rem; }
.metric-grid article { min-width:0; padding:.8rem; border:1px solid var(--line); border-radius:12px; background:var(--panel); }
.metric-grid span,.metric-grid small { display:block; color:var(--muted); font-size:.66rem; }
.metric-grid strong { display:block; margin:.3rem 0; font-size:clamp(1rem,1.5vw,1.25rem); font-variant-numeric:tabular-nums; }

.interpretation-panel { display:grid; grid-template-columns:.75fr 1.25fr; gap:1.5rem; align-items:end; margin-top:.7rem; padding:1rem; border:1px solid var(--line); border-radius:var(--radius); background:var(--bg-soft); }
.interpretation-panel h3 { margin:-.2rem 0 0; }
.interpretation-panel > p { margin:0; color:var(--muted); }

.chapter-pagination { display:grid; grid-template-columns:1fr 1fr; gap:1rem; padding:0 0 4rem; }
.chapter-pagination a { display:grid; padding:1rem; border:1px solid var(--line); border-radius:13px; background:var(--panel); text-decoration:none; }
.chapter-pagination a:last-child { text-align:right; }
.chapter-pagination span { color:var(--muted); font-size:.7rem; }
.chapter-pagination strong { margin-top:.25rem; }
.chapter-pagination a:hover { border-color:var(--accent); }

@media (max-width:1100px) {
  .chapter-hero-grid { grid-template-columns:1fr; }
  .chapter-concept { max-width:820px; }
  .lab-shell { grid-template-columns:1fr; }
  .control-panel { display:grid; grid-template-columns:repeat(3,1fr); gap:0 1rem; }
  .control-head,.control-note { grid-column:1/-1; }
}
@media (max-width:760px) {
  .chapter-hero,.chapter-section,.chapter-pagination { width:min(100% - 1.2rem,var(--max)); }
  .chapter-hero { padding-top:1.4rem; }
  .chapter-hero h1 { font-size:clamp(3rem,15vw,5rem); }
  .concept-grid,.insight-grid { grid-template-columns:1fr; }
  .observation-grid { grid-template-columns:1fr; }
  .control-panel { display:block; }
  .interpretation-panel { grid-template-columns:1fr; align-items:start; }
  .chapter-pagination { grid-template-columns:1fr; }
  .chapter-pagination a:last-child { text-align:left; }
}
@media (max-width:460px) {
  .lab-actions { flex-direction:column; }
}