/* M06-local semantic design tokens used by later optics chapters. */
:root {
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  --sans: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --surface: var(--bg-elevated);
  --panel-strong: var(--panel-solid);
  --success: var(--accent-3);
  --warning: var(--warm);
}

.optics-hero {
  display: grid;
  grid-template-columns: minmax(0,1.35fr) minmax(300px,.65fr);
  gap: 34px;
  align-items: center;
  padding: 74px 0 54px;
  scroll-margin-top: calc(var(--header-h) + 22px);
}
.optics-hero > * { min-width: 0; }
.optics-hero-copy :is(h1,h2) {
  margin: 12px 0 18px;
  max-width: 900px;
  font-size: clamp(2.5rem,5.4vw,5rem);
  line-height: .98;
  letter-spacing: -.052em;
}
.optics-hero-copy :is(h1,h2) em { color: var(--accent); font-style: normal; }
.optics-hero-copy > p { margin: 0; max-width: 780px; color: var(--muted); font-size: 1.06rem; }
.optics-hero-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 28px; }
.optics-hero-card,
.optics-card,
.optics-panel,
.optics-assumption,
.optics-note,
.optics-limits-grid article {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: var(--shadow);
}
.optics-hero-card { padding: 25px; }
.optics-hero-card > span,
.optics-card > span,
.optics-reading > span,
.optics-limits-grid article > span {
  color: var(--accent);
  font-size: .72rem;
  font-weight: 800;
  letter-spacing: .1em;
  text-transform: uppercase;
}
.optics-equation {
  display: grid;
  place-items: center;
  min-height: 70px;
  margin: 14px 0;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: color-mix(in srgb,var(--bg-elevated) 78%,transparent);
  font-family: ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  text-align: center;
}
.optics-equation.large { min-height: 104px; font-size: clamp(1.05rem,2vw,1.35rem); }
.optics-mini-grid { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 8px; }
.optics-mini-grid div { min-width: 0; padding: 11px; border: 1px solid var(--line); border-radius: 12px; background: color-mix(in srgb,var(--panel-solid) 72%,transparent); }
.optics-mini-grid span { display: block; color: var(--muted); font-size: .7rem; }
.optics-mini-grid strong { display: block; margin-top: 4px; font-size: .85rem; overflow-wrap: anywhere; }

.optics-foundation { padding: 42px 0 68px; }
.optics-foundation-grid,
.optics-medium-grid { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 12px; }
.optics-card { padding: 22px; box-shadow: none; }
.optics-card.primary { background: color-mix(in srgb,var(--accent) 8%,var(--panel)); border-color: color-mix(in srgb,var(--accent) 34%,var(--line)); }
.optics-card h3 { margin: 8px 0 8px; font-size: 1.08rem; }
.optics-card p { margin: 8px 0 0; color: var(--muted); font-size: .92rem; }
.optics-axis-sketch { margin: 14px 0; padding: 17px; border-radius: 14px; border: 1px solid var(--line); background: color-mix(in srgb,var(--bg-elevated) 78%,transparent); color: var(--muted); font-family: ui-monospace,SFMono-Regular,Menlo,Consolas,monospace; line-height: 1.8; }
.optics-axis-sketch strong { color: var(--text); }
.optics-note { display: grid; grid-template-columns: 180px minmax(0,1fr); gap: 18px; align-items: start; margin-top: 14px; padding: 20px 22px; box-shadow: none; }
.optics-note strong { color: var(--warm); }
.optics-note p { margin: 0; color: var(--muted); }

.optics-medium { padding: 66px 0; border-block: 1px solid var(--line); background: color-mix(in srgb,var(--bg-elevated) 52%,transparent); }

.optics-lab-section { padding: 72px 0 64px; }
.lab-heading { max-width: 850px; }
.optics-lab-shell { display: grid; grid-template-columns: 288px minmax(0,1fr); gap: 14px; align-items: start; }
.optics-controls {
  position: sticky;
  top: calc(var(--header-h) + 16px);
  display: grid;
  gap: 13px;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: color-mix(in srgb,var(--bg-elevated) 92%,transparent);
  box-shadow: var(--shadow);
}
.optics-control-head { display: flex; align-items: start; justify-content: space-between; gap: 12px; padding-bottom: 4px; }
.optics-control-head > div { display: grid; gap: 3px; }
.optics-control-head span { color: var(--muted); font-size: .72rem; }
.optics-control-head strong { font-size: .88rem; }
.optics-status { min-width: max-content; padding: 4px 7px; border: 1px solid var(--line); border-radius: 999px; color: var(--accent) !important; font-weight: 800; letter-spacing: .04em; }
.optics-controls label { display: grid; grid-template-columns: minmax(0,1fr) auto; gap: 7px 10px; align-items: center; font-size: .78rem; font-weight: 700; }
.optics-controls label > span { min-width: 0; }
.optics-controls output { color: var(--accent); font-family: ui-monospace,SFMono-Regular,Menlo,Consolas,monospace; font-size: .75rem; }
.optics-controls input[type="range"] { grid-column: 1 / -1; width: 100%; accent-color: var(--accent); }
.optics-presets { min-width: 0; margin: 0; padding: 10px; border: 1px solid var(--line); border-radius: 12px; }
.optics-presets legend { padding: 0 5px; color: var(--muted); font-size: .7rem; font-weight: 700; }
.optics-presets > div { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 5px; }
.optics-presets button { min-width: 0; min-height: 36px; padding: 4px 6px; border: 1px solid var(--line); border-radius: 9px; background: var(--panel); color: var(--text); cursor: pointer; font-size: .68rem; font-weight: 750; }
.optics-presets button:hover,
.optics-presets button:focus-visible,
.optics-presets button.is-active { border-color: color-mix(in srgb,var(--accent) 55%,var(--line)); background: color-mix(in srgb,var(--accent) 11%,var(--panel)); }
.optics-reset { width: 100%; }
.optics-assumption { padding: 13px; border-radius: 12px; box-shadow: none; }
.optics-assumption strong { font-size: .76rem; }
.optics-assumption p { margin: 5px 0 0; color: var(--muted); font-size: .71rem; line-height: 1.45; }

.optics-stage { min-width: 0; display: grid; gap: 14px; }
.optics-panel { min-width: 0; padding: 16px; box-shadow: none; }
.optics-panel-head { display: flex; align-items: start; justify-content: space-between; gap: 16px; margin-bottom: 10px; }
.optics-panel-head > div:first-child { display: grid; gap: 3px; }
.optics-panel-head span { color: var(--muted); font-size: .7rem; }
.optics-panel-head strong { font-size: .88rem; }
.optics-readout { text-align: right; }
.optics-readout strong { display: block; color: var(--accent); font-family: ui-monospace,SFMono-Regular,Menlo,Consolas,monospace; font-size: .82rem; }
.optics-detail-grid { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 14px; }
.optics-field-svg,
.optics-compare-svg,
.optics-time-svg { width: 100%; overflow: visible; }
.opt-axis { stroke: var(--line-strong); stroke-width: 1.4; }
.opt-axis.muted { stroke: var(--line); }
.opt-grid-line { stroke: var(--line); stroke-width: 1; }
.opt-wave { fill: none; stroke: var(--accent); stroke-width: 3.4; stroke-linecap: round; stroke-linejoin: round; }
.opt-wave.vacuum { stroke: var(--accent-2); stroke-width: 2.8; }
.opt-wave.medium { stroke: var(--accent); stroke-width: 2.8; }
.opt-wave.time { stroke: var(--accent-3); }
.opt-probe-line { stroke: var(--warm); stroke-width: 1.8; stroke-dasharray: 6 6; }
.opt-field-vector { stroke: var(--warm); stroke-width: 4; stroke-linecap: round; }
.opt-probe-point { fill: var(--warm); stroke: var(--bg-elevated); stroke-width: 3; }
.opt-lambda-line { stroke: var(--accent-3); stroke-width: 2; }
.opt-lambda-cap { stroke: var(--accent-3); stroke-width: 2; }
.opt-lambda-label { fill: var(--accent-3); font: 700 16px ui-monospace,SFMono-Regular,Menlo,Consolas,monospace; }
.opt-svg-label { fill: var(--muted); font: 600 15px Inter,ui-sans-serif,system-ui,sans-serif; }
.opt-svg-label.accent { fill: var(--accent); font-weight: 750; }

.optics-metrics { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 8px; }
.optics-metrics div { min-width: 0; padding: 13px; border: 1px solid var(--line); border-radius: 12px; background: var(--panel); }
.optics-metrics span,.optics-metrics small { display: block; color: var(--muted); font-size: .68rem; }
.optics-metrics strong { display: block; margin: 4px 0 2px; color: var(--text); font-size: .9rem; overflow-wrap: anywhere; }
.optics-reading > span { display: block; margin-bottom: 7px; }
.optics-reading h3 { margin: 0 0 8px; font-size: 1.12rem; }
.optics-reading p { margin: 0; color: var(--muted); font-size: .9rem; }
.optics-checks { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 8px; margin-top: 14px; }
.optics-checks div { padding: 10px; border: 1px solid var(--line); border-radius: 10px; background: color-mix(in srgb,var(--bg-elevated) 62%,transparent); }
.optics-checks span { display: block; color: var(--muted); font-size: .66rem; }
.optics-checks strong { display: block; margin-top: 3px; color: var(--accent-3); font-family: ui-monospace,SFMono-Regular,Menlo,Consolas,monospace; font-size: .72rem; overflow-wrap: anywhere; }
.optics-cross-reference { margin: 18px 0 0; color: var(--muted); font-size: .84rem; }
.optics-cross-reference a { color: var(--text); }

.optics-limits { padding: 48px 0 54px; }
.optics-limits-grid { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 10px; }
.optics-limits-grid article { padding: 18px; border-radius: var(--radius-sm); box-shadow: none; }
.optics-limits-grid strong { display: block; margin-top: 6px; font-size: .98rem; }
.optics-limits-grid p { margin: 7px 0 0; color: var(--muted); font-size: .83rem; }
.optics-next-grid { padding-bottom: 76px; }
.mono { font-family: ui-monospace,SFMono-Regular,Menlo,Consolas,monospace; }

@media (max-width: 980px) {
  .optics-hero { grid-template-columns: 1fr; }
  .optics-hero-card { max-width: 650px; }
  .optics-lab-shell { grid-template-columns: 1fr; }
  .optics-controls { position: static; grid-template-columns: repeat(2,minmax(0,1fr)); }
  .optics-control-head,.optics-presets,.optics-reset,.optics-assumption { grid-column: 1 / -1; }
}

@media (max-width: 760px) {
  .optics-hero { padding-top: 52px; }
  .optics-foundation-grid,.optics-medium-grid,.optics-limits-grid { grid-template-columns: 1fr; }
  .optics-note { grid-template-columns: 1fr; gap: 5px; }
  .optics-detail-grid { grid-template-columns: 1fr; }
  .optics-metrics { grid-template-columns: repeat(2,minmax(0,1fr)); }
  .optics-checks { grid-template-columns: 1fr; }
}

@media (max-width: 520px) {
  .optics-hero > * { min-width: 0; }
.optics-hero-copy :is(h1,h2) { font-size: clamp(2.2rem,12vw,3.5rem); }
  .optics-mini-grid { grid-template-columns: 1fr; }
  .optics-controls { grid-template-columns: 1fr; padding: 14px; }
  .optics-controls label,.optics-control-head,.optics-presets,.optics-reset,.optics-assumption { grid-column: 1; }
  .optics-presets > div { grid-template-columns: 1fr; }
  .optics-metrics { grid-template-columns: 1fr 1fr; }
  .optics-panel { padding: 12px; }
  .opt-svg-label { font-size: 17px; }
  .opt-lambda-label { font-size: 18px; }
}

@media (max-width: 350px) {
  .optics-metrics { grid-template-columns: 1fr; }
  .optics-hero-actions { display: grid; }
}

@media (max-width: 520px) {
  .optics-medium .section-heading h2 { overflow-wrap: anywhere; }
  .optics-controls label,
  .optics-controls input[type="range"] { min-width: 0; }
}