.labs-page, .lab-page { min-width: 0; }
.lab-back { margin-block: 0 14px; }
.labs-index-heading { max-width: 760px; margin: 8px 0 24px; }
.labs-index-heading .page-description { max-width: 62ch; margin-top: 8px; }
.lab-context { margin-top: 8px; color: var(--md-on-surface-variant); font-size: 14px; }
.lab-model-note { max-width: 80ch; margin-block: 14px 20px; padding: 12px 14px; border: 1px solid var(--md-outline-variant); border-radius: 8px; background: var(--md-surface-container-low); color: var(--md-on-surface-variant); font-size: 14px; line-height: 1.5; }

/* A numbered register suits a sequence of prescribed school experiments better than a card grid. */
.labs-index-grid { border-block: 1px solid var(--md-outline-variant); }
.lab-index-card { min-width: 0; border-bottom: 1px solid var(--md-outline-variant); transition: background-color 160ms ease; }
.lab-index-card:last-child { border-bottom: 0; }
.lab-index-card:hover, .lab-index-card:focus-within { background: var(--md-surface-container-low); }
.lab-card-link { min-height: 94px; display: grid; grid-template-columns: 116px minmax(0, 1fr) auto; align-items: center; gap: 16px; padding: 16px 12px; }
.lab-card-number { color: var(--md-primary); font-size: 14px; font-weight: 650; white-space: nowrap; }
.lab-card-copy { min-width: 0; }
.lab-card-copy h2 { font-size: 20px; line-height: 1.35; }
.lab-card-copy > p { max-width: 72ch; margin-top: 5px; color: var(--md-on-surface-variant); line-height: 1.45; }
.lab-card-action { color: var(--md-primary); font-weight: 600; white-space: nowrap; }

.lab-detail-heading { display: flex; align-items: end; justify-content: space-between; gap: 18px; padding-block: 7px 4px; }
.lab-detail-heading > div { min-width: 0; }
.lab-detail-heading .page-title { line-height: 1.15; text-wrap: balance; }
.lab-detail-heading .page-description { max-width: 68ch; margin-top: 9px; line-height: 1.55; }
.lab-lesson-link { flex: 0 0 auto; }
.lab-overview-grid, .lab-notes-grid { display: grid; grid-template-columns: minmax(0, 1.1fr) minmax(260px, .9fr); gap: 14px; margin-block: 16px; }
.lab-panel { min-width: 0; padding: clamp(16px, 3vw, 22px); border: 1px solid var(--md-outline-variant); border-radius: 12px; background: var(--md-surface-container-low); }
.lab-panel h2 { font-size: 20px; line-height: 1.35; }
.lab-walkthrough :is(ol, p) { max-width: 72ch; line-height: 1.6; }
.lab-walkthrough > p { margin-top: 8px; }
.lab-walkthrough > a { margin-top: 12px; }
:is(#lab-walkthrough-title, #lab-stand-title) { scroll-margin-top: 72px; }
:is(#lab-walkthrough-title, #lab-stand-title):focus { outline: 3px solid var(--md-primary); outline-offset: 3px; }
.lab-purpose { display: grid; align-content: start; gap: 9px; background: var(--tone); color: var(--tone-ink); border-color: transparent; }
.lab-purpose > p:last-child, .lab-panel > p { line-height: 1.6; }
.lab-apparatus-list { display: grid; gap: 7px; margin: 12px 0 0; padding-inline-start: 20px; color: var(--md-on-surface-variant); }
.lab-apparatus-list li { padding-inline-start: 2px; line-height: 1.45; }
.lab-procedure { margin-block: 14px; }
.lab-section-heading { margin-bottom: 13px; }
.lab-section-heading h2 { font-size: 20px; }
.lab-section-heading > p { margin-top: 7px; color: var(--md-on-surface-variant); line-height: 1.5; }
.lab-procedure-steps { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 0 24px; margin: 0; padding-inline-start: 1.5rem; }
.lab-procedure-steps li { min-width: 0; padding: 10px 0 10px 4px; border-top: 1px solid var(--md-outline-variant); line-height: 1.5; }
.lab-procedure-steps li::marker { color: var(--md-primary); font-weight: 700; font-variant-numeric: tabular-nums; }

.lab-notebook { min-width: 0; margin-block: 18px; padding: clamp(16px, 3vw, 22px); border: 1px solid var(--md-outline-variant); border-radius: 12px; background: var(--md-surface-container-low); }
.lab-notebook .practice-model { margin: 16px 0; }
.lab-record-actions { display: flex; align-items: center; flex-wrap: wrap; gap: 9px 14px; padding-block: 4px 10px; }
.lab-notebook-status { flex: 1 1 220px; color: var(--md-on-surface-variant); font-size: 14px; }
.lab-trial-list { display: grid; margin-top: 4px; }
.lab-trial-card { min-width: 0; padding-block: 16px; border-top: 1px solid var(--md-outline-variant); }
.lab-trial-heading { display: flex; align-items: center; justify-content: space-between; gap: 12px; }
.lab-trial-heading h3, .lab-calc-title { font-size: 20px; }
.lab-recorded-mark { padding: 5px 10px; border-radius: 999px; background: var(--md-secondary-container); color: var(--md-on-secondary-container); font-size: 12px; font-weight: 600; }
.lab-readings { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 155px), 1fr)); gap: 1px; margin: 14px 0 19px; }
.lab-reading-row { min-width: 0; padding: 10px 12px; background: var(--md-surface-container); }
.lab-reading-row dt { color: var(--md-on-surface-variant); font-size: 14px; line-height: 1.35; }
.lab-reading-row dd { margin-top: 4px; font-size: 1rem; font-weight: 700; font-variant-numeric: tabular-nums; overflow-wrap: anywhere; }
.lab-calculation-form { display: grid; gap: 14px; margin-top: 10px; }
.lab-answer-list { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 245px), 1fr)); gap: 10px; }
.lab-answer-row { display: grid; gap: 6px; min-width: 0; color: var(--md-on-surface); font-weight: 550; }
.lab-answer-label { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 4px 10px; }
.lab-answer-label small { color: var(--md-on-surface-variant); font-weight: 500; }
.lab-answer-input { width: 100%; min-width: 0; min-height: 48px; padding: 9px 12px; border: 1px solid var(--md-outline); border-radius: 8px; background: var(--md-surface); color: var(--md-on-surface); font-variant-numeric: tabular-nums; }
.lab-answer-input:focus-visible { outline: 3px solid var(--md-primary); outline-offset: 2px; }
.lab-form-actions { display: flex; align-items: center; flex-wrap: wrap; gap: 8px 12px; }
.lab-rounding-note { color: var(--md-on-surface-variant); font-size: 14px; }
.lab-check-result { margin-top: 2px; padding: 14px; border-radius: 8px; background: var(--md-surface-container); }
.lab-check-result h3 { font-size: 1rem; }
.lab-check-result > p { margin-top: 5px; color: var(--md-on-surface-variant); }
.lab-check-correct { background: var(--md-primary-container); color: var(--md-on-primary-container); }
.lab-check-review, .lab-check-incomplete { background: var(--md-surface-container-high); }
.lab-worked-results { display: grid; grid-template-columns: minmax(0, 1fr) minmax(130px, auto); gap: 8px 16px; align-items: center; margin-top: 12px; padding-top: 12px; border-top: 1px solid var(--md-outline-variant); }
.lab-worked-results dt { color: var(--md-on-surface-variant); font-size: 14px; }
.lab-worked-results dd { display: flex; align-items: center; justify-content: end; gap: 7px; min-width: 0; text-align: end; font-weight: 650; font-variant-numeric: tabular-nums; }
.lab-worked-results .formula-ink { margin: 0; padding: 0; background: transparent; font-size: 14px; }
.lab-worked-value { white-space: nowrap; }
.lab-notes-grid { margin-top: 15px; }
.lab-fact { background: var(--tone); color: var(--tone-ink); border-color: transparent; }
.lab-fact p { margin-top: 8px; line-height: 1.6; }
.lab-error-note { background: var(--md-surface-container); }
.lab-page-footer { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px; margin-top: 16px; }

@media (max-width: 720px) {
  .lab-detail-heading { align-items: start; flex-direction: column; }
  .lab-lesson-link { align-self: start; }
  .lab-overview-grid, .lab-notes-grid { grid-template-columns: minmax(0, 1fr); }
  .lab-procedure-steps { grid-template-columns: minmax(0, 1fr); }
  .lab-procedure-steps { gap: 0; }
  .lab-worked-results { grid-template-columns: minmax(0, 1fr); gap: 3px; }
  .lab-worked-results dd { justify-content: start; margin-bottom: 7px; text-align: start; }
}

@media (max-width: 460px) {
  .lab-card-link { grid-template-columns: minmax(0, 1fr) auto; gap: 7px 12px; padding: 14px 8px; }
  .lab-card-number { grid-column: 1 / -1; font-size: 12px; }
  .lab-card-action { grid-column: 2; grid-row: 2; font-size: 14px; }
  .lab-card-copy { grid-column: 1; grid-row: 2; }
  .lab-notebook { padding: 13px; }
  .lab-form-actions .practice-button { width: 100%; }
  .lab-rounding-note { width: 100%; }
  .lab-page-footer { flex-direction: column; align-items: stretch; }
  .lab-page-footer .practice-button { justify-content: flex-start; }
}

@media (prefers-reduced-motion: reduce) {
  .lab-index-card { transition: none; }
}

.lab-notebook { margin-block: 24px; padding: 0; border: 0; background: transparent; }
.lab-detail-heading { align-items: center; }
.lab-detail-heading .course-tabs { margin: 0; flex: 0 0 auto; }
.lab-detail-heading .page-title { font-size: clamp(34px, 3.75vw, 54px); }
.lab-notebook .lab-stand {
  display: grid;
  grid-template-columns: minmax(0, 2.1fr) minmax(280px, 1fr);
  align-items: stretch;
  gap: 20px;
  margin: 0;
}
.lab-stand .practice-model-figure {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-width: 0;
  padding: clamp(14px, 2vw, 28px);
  border: 0;
  border-radius: 28px;
  background: #f1eee7;
  color: #1a2230;
  box-shadow: var(--md-elevation-2);
}
.lab-stand .practice-model-canvas { background: #f1eee7; }
.lab-stand .practice-model-plot { width: min(100%, 640px); margin-inline: auto; }
.lab-instrument-header { display: flex; justify-content: space-between; align-items: baseline; gap: 8px; font-size: 21px; }
.model-clock { font-variant-numeric: tabular-nums; font-weight: 700; }
.lab-instrument-header .model-clock { font-size: clamp(18px, 2vw, 28px); white-space: nowrap; }
.lab-stand .practice-measurements {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(100%, 125px), 1fr));
  padding-top: 12px;
  gap: 9px 16px;
  border-top: 1px solid #c3c5c1;
}
.lab-stand .practice-measurements > div { padding: 3px 0; background: transparent; border: 0; }
.lab-stand .practice-measurements dt { color: #545d66; }
.lab-stand .practice-measurements dd { color: #1a2230; font-size: clamp(16px, 2vw, 29px); line-height: 1.2; margin-top: 3px; }
.lab-stand .practice-measurements > div:last-child dd { color: #2549ad; }
.lab-stand-settings {
  min-width: 0;
  display: flex;
  flex-direction: column;
  padding: clamp(16px, 2vw, 28px);
  border-radius: 28px;
  background: var(--md-surface-container);
  box-shadow: var(--md-elevation-2);
}
.lab-stand-settings h2 { font-size: 25px; line-height: 1.3; }
.lab-stand-settings .practice-controls { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; padding-block: 16px 14px; }
.lab-stand-settings .practice-control {
  padding: 9px 10px 1px;
  border: 1px solid var(--md-outline);
  border-radius: 14px;
  background: var(--md-surface-low);
}
.lab-stand-settings .control-caption { flex-direction: column; align-items: start; gap: 3px; color: var(--muted); line-height: 1.28; }
.lab-stand-settings .control-reading { color: var(--ink); font-size: 20px; }
.lab-stand-settings .practice-control input { height: 44px; min-width: 0; }
.lab-stand-settings .model-actions { padding-top: 12px; border-top: 1px solid var(--line); margin-top: auto; }
.lab-stand-settings .model-actions .practice-button { flex: 1 1 auto; }
.lab-stand-settings > .practice-button { width: 100%; margin-top: 10px; }
.lab-stand-settings > .practice-button:disabled { background: var(--md-surface-low); color: var(--muted); opacity: 1; border-color: var(--line); }
.lab-stand .scene-grip::before { background: #f8f6f1; border-color: #2549ad; box-shadow: 0 0 0 2px #f1eee7; }
.lab-stand .scene-grip:active::before { background: #2549ad; }
.lab-series-title { margin-block: 27px 10px; font-size: 24px; }
.lab-notebook-status:empty { display: none; }
.lab-panel { border-radius: 20px; }

@media (max-width: 810px) {
  .lab-notebook .lab-stand { grid-template-columns: minmax(0, 1fr); gap: 16px; }
  .lab-stand .practice-model-figure, .lab-stand-settings { border-radius: 24px; }
}
@media (max-width: 460px) {
  .lab-detail-heading { align-items: start; }
  .lab-detail-heading .course-tabs { display: none; }
  .lab-instrument-header { font-size: 16px; }
  .lab-stand .practice-measurements { grid-template-columns: repeat(2, minmax(0,1fr)); }
  .lab-stand-settings .practice-control { padding-inline: 8px; }
}

.lab-stand-status { margin-block: 8px 16px; min-block-size: 3em; color: var(--md-on-surface-variant); line-height: 1.45; }
.lab-assembly-tools, .lab-parts, .lab-dock { display: grid; gap: 8px; min-width: 0; }
.lab-build-help { font-size: 14px; line-height: 1.45; color: var(--md-on-surface-variant); }
.lab-assembly-tools > .practice-button { justify-self: start; }
.lab-parameter-title { margin-top: 18px; }
.lab-parts, .lab-dock { grid-template-columns: repeat(auto-fit, minmax(min(100%, 115px), 1fr)); }
.lab-placement { display: grid; gap: 12px; margin-block: 8px 16px; }
.lab-parts { padding-block-start: 10px; border-block-start: 1px solid #c3c5c1; }
.lab-stand .practice-button:is(.lab-part, .lab-target) {
  min-block-size: 44px;
  padding: 7px 10px;
  white-space: normal;
  line-height: 1.25;
  touch-action: none;
  user-select: none;
}
.lab-part, .lab-port { cursor: grab; }
.lab-part[aria-pressed="true"] { background: var(--md-secondary-container); color: var(--md-on-secondary-container); }
.lab-stand .lab-target, .lab-stand .lab-part {
  background: #f8f6f1;
  color: #1a2230;
  border: 1px solid #7b8792;
  border-radius: 10px;
}
.lab-stand .lab-target { border-style: dashed; }
.lab-stand .practice-button:is(.lab-target, .lab-part):is([aria-pressed="true"], .lab-dragging) {
  background: #d9e5ff;
  color: #163577;
  border-color: #2549ad;
  border-style: solid;
}
.lab-stand .lab-dragging { cursor: grabbing; outline: 2px solid #2549ad; outline-offset: 2px; }
.lab-stand .practice-button:focus-visible { outline: 3px solid var(--md-primary); outline-offset: 3px; }
.lab-stand .practice-model-figure .practice-button:focus-visible { outline-color: #2549ad; }
.lab-travel { grid-column: 1 / -1; }
.lab-stand .lab-load-grip { z-index: 2; }
/* Keep Safari from shifting the page when the circuit readouts redraw. */
html:has(.lab-electric-stand) { overflow-anchor: none; }
.lab-notebook .lab-electric-stand {
  grid-template-columns: minmax(0, 1fr) minmax(278px, 32%);
  align-items: start;
  gap: 16px;
}
.lab-circuit-panel, .lab-circuit-aside .lab-stand-settings, .lab-circuit-instrument {
  min-width: 0;
  padding: clamp(12px, 2vw, 24px);
  border: 1px solid #e5e7eb;
  border-radius: 16px;
  background: #fff;
  box-shadow: none;
}
.lab-circuit-panel { container-type: inline-size; }
.lab-circuit-heading {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 4px 12px;
}
.lab-circuit-heading h2 { font-size: clamp(21px, 2.4vw, 26px); line-height: 1.3; }
.lab-circuit-progress {
  color: #273c9c;
  font: 600 12px/1.4 var(--bright-mono, monospace);
  white-space: nowrap;
}
.lab-circuit-progress.is-complete { color: #176141; }
.lab-circuit-panel .lab-build-help { margin-block: 8px 12px; }
.lab-circuit-status {
  margin-bottom: 12px;
  padding: 9px 12px;
  border: 1px solid #cbd4ff;
  border-radius: 8px;
  background: #eef2ff;
  color: #233572;
}
.lab-circuit-status .lab-stand-status {
  min-block-size: 2.9em;
  margin: 0;
  color: inherit;
  font-size: 14px;
}
.lab-circuit-status.has-error { background: #fff0ec; border-color: #e6a499; color: #852d24; }
.lab-circuit-status.is-powered { background: #e7f5ee; border-color: #b9dece; color: #176141; font-weight: 650; }
.lab-circuit-status .lab-remove-wire { margin-top: 6px; border-color: #ab594d; color: #852d24; background: #fff; }
.lab-circuit-status .lab-remove-wire:hover { background: #ffded5; }
.lab-circuit-status .lab-remove-wire[hidden] { display: none; }
.lab-circuit { min-width: 0; margin-bottom: 12px; }
.lab-circuit-board {
  position: relative;
  isolation: isolate;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px 6px;
  padding: 10px 4px 28px;
  border-radius: 10px;
  background: #f5f7ff radial-gradient(circle at 1px 1px, #d9e0f5 1px, transparent 1px) 0 0 / 12px 12px;
}
.lab-circuit-drawing {
  position: absolute;
  z-index: -1;
  inset: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  pointer-events: none;
}
.lab-terminal-group {
  min-width: 0;
  display: grid;
  grid-template-rows: minmax(20px, auto) 44px;
  justify-items: center;
  gap: 3px;
}
.lab-terminal-group h3 {
  align-self: start;
  padding-inline: 3px;
  background: #f5f7ff;
  color: #253972;
  font-size: 12px;
  text-align: center;
}
.lab-terminal-row { display: flex; align-items: center; justify-content: center; }
.lab-stand .practice-button.lab-port {
  display: grid;
  width: 44px;
  height: 44px;
  min-height: 44px;
  flex: 0 0 44px;
  place-items: center;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: transparent;
  color: #253972;
  box-shadow: none;
  cursor: grab;
  touch-action: none;
  user-select: none;
}
.lab-stand .practice-button.lab-port.lab-dragging { cursor: grabbing; }
.lab-port span {
  display: grid;
  width: 26px;
  height: 26px;
  place-items: center;
  border: 1.5px solid #7686bf;
  border-radius: 50%;
  background: #fff;
  font: 600 14px/1 var(--bright-mono, monospace);
  transition: background 180ms ease, color 180ms ease, box-shadow 180ms ease;
}
.lab-port:is(:hover, :focus-visible) span { background: #e8edff; }
.lab-port:is([aria-pressed="true"], .lab-dragging) span {
  border-color: #2044f4;
  background: #2044f4;
  color: #fff;
  box-shadow: 0 0 0 4px #b7c3ff;
}
.lab-component-symbol { width: 26px; height: 24px; flex: none; background: #f5f7ff; }
.lab-component-symbol text { text-anchor: middle; font-size: 24px; font-weight: 750; fill: #253972; }
.lab-component-shape { stroke: #253972; fill: none; stroke-width: 4; stroke-linecap: round; stroke-linejoin: round; }
.lab-circuit-drawing path { fill: none; stroke-linejoin: round; stroke-linecap: round; }
.lab-wire-bridge { stroke: #fff; stroke-width: 6; }
.lab-wire { stroke: #314ac1; stroke-width: 2.8; }
.lab-wire-error { stroke: #ad3d31; stroke-width: 3.2; stroke-dasharray: 4 3; }
.lab-wire-preview { stroke: #6b44cd; stroke-width: 2.5; stroke-dasharray: 3 5; }
.lab-wire-current { stroke: #f98a48; stroke-width: 3; }
.lab-flowing .lab-wire-current { stroke-dasharray: 3 8; animation: lab-flow 560ms linear 5; }
@keyframes lab-flow { to { stroke-dashoffset: -11; } }
.lab-circuit-panel .lab-circuit-actions { margin: 0; }
.lab-circuit-actions .practice-button,
.lab-circuit-instrument > .practice-button,
.lab-circuit-status .lab-remove-wire { min-height: 44px; border-radius: 8px; padding-inline: 12px; }
.lab-circuit-panel .lab-circuit-actions .practice-button:not(:hover, :focus-visible) { box-shadow: none; }
.lab-circuit-guide { margin-top: 8px; color: #4b5563; font-size: 14px; }
.lab-circuit-guide summary { min-height: 44px; padding-block: 10px; color: #2044f4; font-weight: 650; cursor: pointer; }
.lab-circuit-guide ol { margin: 0; padding-inline-start: 20px; }
.lab-wires { margin-top: 8px; padding: 0; list-style: none; }
.lab-wires:empty { display: none; }
.lab-wires li { display: flex; align-items: center; justify-content: space-between; gap: 6px; border-top: 1px solid #e5e7eb; }
.lab-wires .practice-button { min-height: 44px; flex: none; }
.lab-circuit-aside { display: grid; gap: 16px; }
.lab-circuit-instrument { background: #192344; color: #fff; border-color: #192344; }
.lab-circuit-aside h3 { font-size: 19px; }
.lab-circuit-instrument .practice-measurements {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px 8px;
  margin-block: 12px;
  padding: 0;
  border: 0;
}
.lab-circuit-instrument .practice-measurements > div { padding-top: 6px; border-top: 1px solid #51618e; border-radius: 0; }
.lab-circuit-instrument .practice-measurements dt { color: #dbe4ff; font-size: 12px; }
.lab-circuit-instrument .practice-measurements dd,
.lab-circuit-instrument .practice-measurements > div:last-child dd { color: #fff; font: 600 17px/1.3 var(--bright-mono, monospace); }
.lab-circuit-instrument > .practice-button { background: #fff; border-color: #fff; color: #111827; }
.lab-circuit-instrument > .practice-button:disabled { background: #3a4870; border-color: #3a4870; color: #fff; opacity: 1; }
.lab-circuit-instrument > .practice-button:focus-visible { outline-color: #fff; }
.lab-circuit-aside .practice-controls { grid-template-columns: minmax(0, 1fr); padding-bottom: 0; }
.lab-circuit-aside .practice-control { padding: 0; border: 0; background: #fff; }
.lab-circuit-aside .control-caption { flex-direction: row; align-items: baseline; flex-wrap: wrap; }
.lab-circuit-aside .control-reading { color: #273c9c; font: 600 14px/1.4 var(--bright-mono, monospace); }
.lab-range-limits { display: flex; justify-content: space-between; color: #4b5563; font-size: 12px; }
@container (max-width: 370px) {
  .lab-circuit-board { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media (max-width: 810px) {
  .lab-notebook .lab-electric-stand { grid-template-columns: minmax(0, 1fr); }
}
@media (min-width: 560px) and (max-width: 810px) {
  .lab-circuit-aside { grid-template-columns: repeat(2, minmax(0, 1fr)); align-items: start; }
}
@media (prefers-reduced-motion: reduce) {
  .lab-port span, .lab-electric-stand .practice-button { transition: none; }
  .lab-flowing .lab-wire-current { animation: none; stroke-dasharray: none; }
}
.lab-heater-water {
  display: flex; position: relative; align-items: center; gap: 16px; width: max-content; margin: 4px auto 0;
  border: 2px solid #496077; border-top: 0; border-radius: 0 0 14px 14px; padding: 7px 14px;
  background: color-mix(in srgb, #d9e5ff, #edaa83 calc(100% * var(--heater-rise, 0))); font-weight: 650;
}
.lab-water-level { position: relative; display: block; width: 12px; height: 44px; border: 2px solid #496077; border-radius: 6px; background: #f8f6f1; }
.lab-water-level::after {
  content: ""; position: absolute; inset-inline: 1px; bottom: 1px; height: calc(4px + 31px * var(--heater-rise, 0));
  border-radius: 4px; background: #a7472f;
}

/* Physics demonstrations */
.lab-demo {
  --diagram-paper: #f1eee7;
  --diagram-ink: #1a2230;
  --branch-one: #247379;
  --branch-two: #a54539;
  min-width: 0;
}
.lab-demo > .page-title { margin-block: 12px 18px; }
.lab-demo > .demo-subline { margin-block: -5px 20px; }
.demo-grid { display: grid; grid-template-columns: minmax(0, 1.9fr) minmax(250px, 1fr); gap: 24px; align-items: start; }
.demo-instrument { margin: 0; overflow: hidden; border-radius: 20px; background: var(--diagram-paper); color: var(--diagram-ink); }
.demo-instrument figcaption { padding: 8px 20px 16px; font-size: 14px; }
.lab-demo .circuit { display: block; width: 100%; height: auto; -webkit-user-select: none; user-select: none; }
.circuit :is(.wire, .switch-blade, .terminal-mark, .direction) { fill: none; stroke-linecap: round; stroke-linejoin: round; }
.circuit .wire { stroke: #64636b; stroke-width: 4; }
.circuit .wire-link { visibility: hidden; stroke: var(--branch-one); stroke-width: 5; }
.circuit .wire-gap { stroke: #77727b; stroke-dasharray: 4 8; stroke-width: 2.5; }
.circuit[data-wire="true"] .wire-link { visibility: visible; }
.circuit[data-wire="true"] .wire-gap { visibility: hidden; }
.circuit .switch-blade { stroke: #3b4451; stroke-width: 6; transform: rotate(-28deg); transform-origin: 259px 82px; transition: transform 180ms cubic-bezier(.16, 1, .3, 1); }
.circuit[data-key="true"] .switch-blade { transform: none; }
.circuit .terminal-mark { stroke: var(--diagram-ink); stroke-width: 5; }
.circuit :is(.contact, .part) { fill: #f8f5ed; stroke: #3b4451; stroke-width: 3.5; }
.circuit .bridge-contact { fill: transparent; cursor: pointer; touch-action: none; }
.circuit .bridge-marker { pointer-events: none; }
.circuit .bridge-contact:is(:hover, .is-selected) + .bridge-marker { fill: #a6d5cb; stroke: var(--branch-one); }
.circuit .wire-preview { stroke: var(--branch-one); stroke-width: 4; stroke-dasharray: 6 5; pointer-events: none; }
.circuit .junction { fill: var(--diagram-ink); }
.circuit .first-part { fill: #c5e3dc; stroke: var(--branch-one); }
.circuit .second-part { fill: #edd5cd; stroke: var(--branch-two); }
.circuit .diagram-label { fill: var(--diagram-ink); font-size: 26px; font-weight: 750; }
.circuit .diagram-note { fill: #4b4e56; font-size: 24px; font-weight: 550; }
.circuit .direction { visibility: hidden; stroke: #3b4451; stroke-width: 3.5; }
.circuit[data-powered="true"] .direction { visibility: visible; }
.circuit .flow { fill: none; visibility: hidden; stroke-linecap: round; stroke-width: 5; }
.circuit .common-flow { stroke: #414f92; }
.circuit .first-flow { stroke: var(--branch-one); }
.circuit .second-flow { stroke: var(--branch-two); }
.circuit[data-powered="true"] .flow { visibility: visible; stroke-dasharray: 6 15; animation: wire-flow var(--period, 1.4s) linear infinite; }
@keyframes wire-flow { to { stroke-dashoffset: -21; } }

.demo-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-block: 15px 6px; }
.demo-state { min-height: 26px; margin-block: 8px 4px; color: var(--md-on-surface-variant); font-size: 15px; }
.demo-controls { padding: 20px; border-radius: 20px; background: var(--md-surface-container-low); min-width: 0; }
.demo-controls h2 { margin: 0 0 14px; font-size: 21px; line-height: 1.25; }
.demo-readings { margin: 0 0 16px; display: grid; gap: 6px; }
.demo-readings div, .demo-range-label { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; }
.demo-readings dd { margin: 0; font-weight: 720; font-size: 21px; font-variant-numeric: tabular-nums; }
.demo-readings dt, .demo-range-label { color: var(--md-on-surface-variant); }
.demo-readings > :last-child { border-top: 1px solid var(--md-outline-variant); padding-top: 7px; }
.demo-equation { margin: 8px 0 18px; color: var(--md-primary); font-size: 15px; }
.demo-equation span { display: block; }
.demo-ranges { display: grid; gap: 13px; }
.demo-range-label { font-size: 15px; }
.demo-range-label output { color: var(--md-on-surface); font-variant-numeric: tabular-nums; font-weight: 650; white-space: nowrap; }
.demo-ranges input { width: 100%; margin: 5px 0 0; height: 32px; accent-color: var(--md-primary); }
:is(.lab-stand-settings, .demo-ranges) input[type="range"]:enabled { touch-action: none; }

.sim-grid { grid-template-columns: minmax(0, 1fr) minmax(240px, 310px); }
.sim-picker { grid-area: 1 / 2; }
.sim-stage { grid-area: 1 / 1; min-width: 0; aspect-ratio: 16 / 10; }
.sim-stage iframe { display: block; width: 100%; height: 100%; border: 0; }
.sim-credit { color: var(--md-on-surface-variant); font-size: 14px; margin: 12px 0 0; }
.sim-credit a { text-decoration: underline; text-underline-offset: 3px; }
.sim-picker select {
  display: block;
  width: 100%;
  min-height: 48px;
  margin-block: 9px;
  padding: 8px 10px;
  background: var(--md-surface);
  border: 1px solid var(--md-outline-variant);
  border-radius: 10px;
  color: inherit;
}

@media (max-width: 1100px) {
  .demo-grid { gap: 14px; }
}
@media (max-width: 760px) {
  .demo-grid { grid-template-columns: minmax(0, 1fr); }
  .demo-instrument figcaption { padding: 7px 12px 12px; font-size: 13px; }
  .sim-picker, .sim-stage { grid-area: auto; }
  .sim-stage { aspect-ratio: 4 / 3; }
}
@media (prefers-reduced-motion: reduce) {
  .lab-demo .circuit, .lab-demo .circuit * { transition-property: none; }
  .circuit[data-powered="true"] .flow { animation: none; stroke-dasharray: none; }
}