.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, SFMono-Regular, Menlo, 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, SFMono-Regular, Menlo, 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; }

.dual-view {
  display: grid; grid-template-columns: .9fr 1.1fr; gap: .65rem;
  padding: .75rem;
}
.attitude-panel, .response-panel {
  min-width: 0;
  border: 1px solid var(--line); border-radius: 14px;
  background: var(--nav-bg); overflow: hidden;
}
#attitudeSvg, #responsePlot { width: 100%; height: auto; display: block; }
.plot-bg { fill: var(--nav-bg); }
.flow-axis { stroke: var(--line-strong); stroke-width: 2; stroke-dasharray: 8 8; }
.body-shape { fill: color-mix(in srgb, var(--panel-2) 82%, var(--accent) 18%); stroke: var(--text); stroke-width: 2; }
.fin-shape { fill: var(--panel-2); stroke: var(--text); stroke-width: 2; }
.cg-marker { fill: var(--accent-2); stroke: var(--nav-bg); stroke-width: 2; }
.cp-marker { fill: var(--danger); stroke: var(--nav-bg); stroke-width: 2; }
.force-vector { stroke: var(--accent); stroke-width: 4; stroke-linecap: round; }
.angle-arc { fill: none; stroke: var(--muted); stroke-width: 2; }
.attitude-label {
  fill: var(--text); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 12px;
}
.attitude-label.muted { fill: var(--muted); }

.grid-line { stroke: var(--line); stroke-width: 1; opacity: .8; }
.axis-line { stroke: var(--line-strong); stroke-width: 1.2; }
.axis-text {
  fill: var(--muted); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 11px;
}
.response-path { fill: none; stroke: var(--accent); stroke-width: 3; stroke-linejoin: round; stroke-linecap: round; }
.time-cursor { stroke: var(--accent-2); stroke-width: 2; stroke-dasharray: 5 5; }

.attitude-readout {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: .4rem;
  padding: .65rem; border-top: 1px solid var(--line);
}
.attitude-readout span {
  display: grid; gap: .1rem; color: var(--muted);
  font-size: .65rem;
}
.attitude-readout strong { color: var(--text); font-size: .82rem; font-variant-numeric: tabular-nums; }

.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-dot { width: 8px; height: 8px; border-radius: 50%; }
.legend-dot.cg { background: var(--accent-2); }
.legend-dot.cp { background: var(--danger); }
.legend-vector.force { width: 18px; height: 0; border-top: 3px solid var(--accent); }

.control-panel { padding: 1rem; }
.control-head h3 { margin: -.25rem 0 1rem; }
.control { padding: .85rem 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(6, 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: 1040px) {
  .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(2, 1fr); gap: 0 1rem; }
  .control-head, .control-note { grid-column: 1 / -1; }
  .metric-grid { grid-template-columns: repeat(3, 1fr); }
}
@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; }
  .dual-view { grid-template-columns: 1fr; }
  .control-panel { display: block; }
  .metric-grid { grid-template-columns: 1fr 1fr; }
  .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) {
  .metric-grid { grid-template-columns: 1fr; }
  .lab-actions { flex-direction: column; }
  .attitude-readout { grid-template-columns: 1fr; }
}