/*
 * heat-protein-lab — design tokens + Chapter 1 layout.
 * Tokens follow DESIGN.md. Phase 1 scaffolds Chapter 0 hero + Chapter 1.
 */

:root {
  /* Heat ramp (DESIGN.md § Visual system) */
  --paper: #f5efdf;
  --paper-edge: #e9e0c8;
  --ink: #1b1b1b;
  --ink-soft: #3d3a33;
  --ink-faint: #8a8275;
  --rule: #221a15;

  --heat-37: #4f6b7a;
  --heat-38: #6e7c73;
  --heat-39: #b8a04f;
  --heat-40: #c97a2b;
  --heat-41: #b23a1f;
  --heat-42: #7f1414;
  --heat-44: #1b0707;

  --accent-link: var(--heat-42);
  --accent-link-hover: var(--heat-41);
  --surface-card: #fbf6e8;
  --surface-viewer: #0f1217;

  /* Type */
  --font-display: "GT Sectra Display", "Spectral", "Charter", Georgia, serif;
  --font-body: "Spectral", "Charter", Georgia, serif;
  --font-mono: "IBM Plex Mono", "JetBrains Mono", ui-monospace, "SF Mono",
    Menlo, monospace;
  --font-ui: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;

  /* Layout */
  --reading-max: 64ch;
  --gutter: clamp(1rem, 4vw, 2rem);
  --section-gap-y: clamp(96px, 12vw, 192px);
  --temp-strip-height: 4px;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  scroll-behavior: smooth;
}

/* ---------- Skip to content (keyboard accessibility) ---------- */
.skip-link {
  position: absolute;
  top: -100px;
  left: 8px;
  background: var(--ink);
  color: var(--paper);
  padding: 0.5rem 1rem;
  font-family: var(--font-ui);
  font-size: 0.9rem;
  text-decoration: none;
  border-radius: 2px;
  z-index: 200;
  transition: top 240ms cubic-bezier(0.4, 0, 0.2, 1);
}
.skip-link:focus {
  top: 8px;
  outline: 2px solid var(--heat-39);
  outline-offset: 2px;
}

body {
  margin: 0;
  min-height: 100vh;
  font-size: clamp(1.0625rem, 0.95rem + 0.4vw, 1.1875rem);
}

main {
  display: block;
}

a {
  color: var(--accent-link);
  text-decoration: underline;
  text-underline-offset: 2px;
}
a:hover,
a:focus-visible {
  color: var(--accent-link-hover);
}

.mono {
  font-family: var(--font-mono);
  font-size: 0.92em;
  letter-spacing: 0.01em;
}

/* ---------- Persistent global UI: temperature strip ---------- */

.temp-strip {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--temp-strip-height);
  background: var(--paper-edge);
  z-index: 100;
  pointer-events: none;
}

.temp-strip__fill {
  height: 100%;
  width: var(--fill-width, 5%);
  background: var(--heat-37);
  transition: width 240ms cubic-bezier(0.4, 0, 0.2, 1),
    background 240ms cubic-bezier(0.4, 0, 0.2, 1);
}

.temp-strip__readout {
  position: fixed;
  top: calc(var(--temp-strip-height) + 6px);
  right: calc(var(--gutter) + 88px); /* leave room for unit-toggle */
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-soft);
  z-index: 100;
  pointer-events: none;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

/* ---------- Celsius / Fahrenheit toggle ---------- */
.unit-toggle {
  position: fixed;
  top: calc(var(--temp-strip-height) + 6px);
  right: var(--gutter);
  z-index: 101;
  display: inline-flex;
  align-items: stretch;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  border: 1px solid var(--paper-edge);
  background: var(--surface-card);
  border-radius: 999px;
  overflow: hidden;
  user-select: none;
}
.unit-toggle__btn {
  appearance: none;
  border: 0;
  background: transparent;
  color: var(--ink-soft);
  cursor: pointer;
  padding: 4px 10px;
  font: inherit;
  letter-spacing: 0.04em;
  transition: background 0.14s ease, color 0.14s ease;
}
.unit-toggle__btn:hover {
  color: var(--ink);
}
.unit-toggle__btn[aria-pressed="true"] {
  background: var(--ink);
  color: var(--paper);
}
.unit-toggle__btn:focus-visible {
  outline: 2px solid var(--heat-39);
  outline-offset: 2px;
}

@media (max-width: 480px) {
  .unit-toggle {
    font-size: 0.65rem;
  }
  .unit-toggle__btn {
    padding: 4px 8px;
  }
  .temp-strip__readout {
    right: calc(var(--gutter) + 76px);
  }
}

/* ---------- Plate corner badge ---------- */

.plate-corner {
  position: fixed;
  bottom: 16px;
  right: var(--gutter);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
  background: var(--surface-card);
  border: 1px solid var(--paper-edge);
  padding: 6px 10px;
  border-radius: 2px;
  z-index: 90;
  user-select: none;
  pointer-events: none;
}

@media (max-width: 480px) {
  .plate-corner {
    display: none;
  }
}

/* ---------- Chapter shell ---------- */

.chapter {
  min-height: 100vh;
  min-height: 100dvh;
  padding: var(--section-gap-y) var(--gutter);
  display: flex;
  align-items: center;
  border-bottom: 1px solid transparent;
}

.chapter:not(:last-of-type) {
  border-bottom-color: var(--paper-edge);
}

.chapter__inner {
  width: 100%;
  max-width: 1440px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(24px, 4vw, 48px);
}

@media (min-width: 1024px) {
  .chapter__inner {
    grid-template-columns: 20% minmax(0, 50%) minmax(0, 30%);
    gap: clamp(32px, 4vw, 64px);
    align-items: start;
  }
}

.chapter__inner--stub {
  grid-template-columns: 1fr;
  text-align: left;
  max-width: 80ch;
}

/* Hero chapter is type-only; collapse columns */
.chapter--hero .chapter__inner {
  grid-template-columns: 1fr;
  max-width: 80ch;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-soft);
  margin: 0 0 1rem 0;
}

.chapter__title {
  font-family: var(--font-display);
  font-weight: 500;
  line-height: 1.05;
  letter-spacing: -0.01em;
  margin: 0 0 1.25rem 0;
  font-size: clamp(1.75rem, 1.2rem + 2vw, 2.625rem);
  color: var(--ink);
}

.chapter__title--hero {
  font-size: clamp(4rem, 3rem + 6vw, 7rem);
  letter-spacing: -0.02em;
  margin-top: 0.5rem;
}

.rule {
  border: 0;
  border-top: 1px solid var(--rule);
  margin: 1.5rem 0 1.5rem 0;
  max-width: 6rem;
}

.lede {
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 1rem + 1vw, 1.5rem);
  line-height: 1.4;
  color: var(--ink);
  margin: 0 0 2rem 0;
  font-style: italic;
}

.body {
  margin: 0 0 1rem 0;
  max-width: var(--reading-max);
}

.body + .body {
  margin-top: 1.25rem;
}

.stub-note {
  color: var(--ink-soft);
  font-style: italic;
}

/* ---------- "What this is not" list ---------- */

.not-list {
  margin: 2rem 0 0 0;
  padding: 1rem 1.25rem;
  border-left: 2px solid var(--rule);
  background: rgba(34, 26, 21, 0.03);
}

.not-list__heading {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-soft);
  margin: 0 0 0.5rem 0;
}

.not-list ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

.not-list li {
  font-family: var(--font-mono);
  font-size: 0.92rem;
  color: var(--ink-soft);
  padding: 0.2rem 0;
}

.not-list li::before {
  content: "—";
  color: var(--ink-faint);
  margin-right: 0.6em;
}

/* ---------- Chapter 1 layout pieces ---------- */

.marginalia {
  font-size: 0.9rem;
  color: var(--ink-soft);
}

.marginalia .eyebrow {
  margin-bottom: 0.5rem;
}

.margin-temp {
  font-family: var(--font-mono);
  margin: 0 0 1.5rem 0;
  color: var(--ink-soft);
  letter-spacing: 0.03em;
}

.badge {
  border-top: 1px solid var(--paper-edge);
  border-bottom: 1px solid var(--paper-edge);
  padding: 1rem 0;
  margin-top: 1.5rem;
}

.badge__label {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 0 0 0.5rem 0;
}

.badge__body {
  margin: 0 0 0.5rem 0;
  font-size: 0.95rem;
  color: var(--ink);
}

.badge__source {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--ink-faint);
  letter-spacing: 0.04em;
}

.reading {
  /* explicit max-width to enforce 64ch even at large viewports */
  max-width: var(--reading-max);
}

.figure {
  display: flex;
  justify-content: flex-start;
}

/* Sticky figure on desktop — protein stays visible while reading body text */
@media (min-width: 1024px) {
  .figure {
    position: sticky;
    top: calc(var(--temp-strip-height) + 32px);
    align-self: start;
  }
}

/* Two-figure stack (Ch 2: schematic + viewer) */
.figure--stacked {
  flex-direction: column;
  gap: 24px;
  width: 100%;
}

/* ---------- Schematic card (Ch 2 monomer -> trimer diagram) ---------- */

.schematic-card {
  margin: 0;
  width: 100%;
  max-width: 360px;
  background: var(--surface-card);
  border: 1px solid var(--paper-edge);
  border-radius: 4px;
  padding: 12px 16px 8px;
}

.schematic-banner {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--heat-41);
  margin: 0 0 8px 0;
  text-align: center;
  border-bottom: 1px dashed var(--heat-41);
  padding-bottom: 6px;
}

.schematic {
  display: block;
  width: 100%;
  height: auto;
  margin: 0 auto;
}

.schematic__label {
  font-family: var(--font-mono);
  font-size: 9px;
  letter-spacing: 0.04em;
  fill: var(--ink);
}

.schematic__sublabel {
  font-family: var(--font-mono);
  font-size: 8px;
  letter-spacing: 0.04em;
  fill: var(--ink-faint);
}

.schematic__heat {
  fill: var(--heat-41);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.schematic-caption {
  margin: 4px 0 0 0;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--ink-faint);
  text-align: center;
}

/* Compact variant of the viewer card for when it's stacked below a schematic */
.viewer-card--compact .viewer {
  aspect-ratio: 4 / 3;
}

/* ---------- Chapter 4 centerpiece: scroll-driven denaturation ---------- */

.chapter--centerpiece {
  /* Tall section so we have scroll budget for the sticky stage */
  min-height: 250vh;
  padding: 0 var(--gutter);
  display: block;
  align-items: stretch;
  border-bottom: 1px solid var(--paper-edge);
}

.ch4-sticky {
  position: sticky;
  top: 0;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding-top: calc(var(--temp-strip-height) + 16px);
  padding-bottom: 16px;
}

.ch4-stage {
  width: 100%;
  max-width: 1200px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.ch4-eyebrow {
  margin: 0 0 8px 0;
  text-align: center;
}

.ch4-banner {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--paper);
  background: var(--heat-41);
  padding: 6px 16px;
  border-radius: 2px;
  margin: 0 0 14px 0;
  text-align: center;
}

.chapter__title--centerpiece {
  font-size: clamp(2rem, 1.3rem + 2.4vw, 3rem);
  text-align: center;
  margin: 0 0 18px 0;
}

.ch4-row {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
  width: 100%;
  align-items: center;
}

@media (min-width: 1024px) {
  .ch4-row {
    grid-template-columns: minmax(0, 1fr) minmax(0, 360px);
  }
}

.viewer-card--centerpiece {
  margin: 0;
  width: 100%;
  max-width: 560px;
  justify-self: center;
}

.viewer-card--centerpiece .viewer {
  aspect-ratio: 1 / 1;
}

.ch4-side {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.ch4-temp-readout {
  display: flex;
  align-items: baseline;
  gap: 6px;
  justify-content: center;
}

.ch4-temp-value {
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 2rem + 2vw, 3.6rem);
  line-height: 1;
  color: var(--ink);
  font-variant-numeric: tabular-nums;
  transition: color 240ms cubic-bezier(0.4, 0, 0.2, 1);
}

.ch4-temp-unit {
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 1rem + 0.8vw, 1.6rem);
  color: var(--ink-soft);
}

.ch4-tm-marker {
  text-align: center;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  color: var(--ink-soft);
  border-top: 1px dashed var(--rule);
  padding-top: 6px;
}

.ch4-metrics {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.metric {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.metric__row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-size: 0.82rem;
}

.metric__label {
  font-family: var(--font-mono);
  color: var(--ink-soft);
  letter-spacing: 0.02em;
}

.metric__value {
  color: var(--ink);
  font-variant-numeric: tabular-nums;
}

.metric__bar {
  height: 4px;
  background: var(--paper-edge);
  border-radius: 2px;
  overflow: hidden;
}

.metric__bar-fill {
  height: 100%;
  width: 0%;
  background: var(--heat-37);
  transition: width 240ms cubic-bezier(0.4, 0, 0.2, 1),
    background 240ms cubic-bezier(0.4, 0, 0.2, 1);
}

.ch4-side-note {
  margin: 4px 0 0 0;
  font-family: var(--font-body);
  font-size: 0.85rem;
  line-height: 1.5;
  color: var(--ink-soft);
  font-style: italic;
}

.chapter--ch4-outro .chapter__inner {
  grid-template-columns: 1fr;
  justify-items: center;
}

.chapter--ch4-outro {
  min-height: auto;
  padding-top: 96px;
  padding-bottom: 96px;
}

.reading--centerpiece-outro {
  max-width: var(--reading-max);
}

@media (prefers-reduced-motion: reduce) {
  .ch4-sticky {
    position: static;
    height: auto;
    padding-top: 32px;
    padding-bottom: 32px;
  }
  .chapter--centerpiece {
    min-height: auto;
  }
}

/* ---------- Chapter 5: HPA tissue heatmap ---------- */

.figure--heatmap {
  flex-direction: column;
  width: 100%;
}

.heatmap-card {
  margin: 0;
  width: 100%;
  background: var(--surface-card);
  border: 1px solid var(--paper-edge);
  border-radius: 4px;
  padding: 14px 14px 12px;
}

.heatmap {
  display: grid;
  /* tissue label | three gene cells */
  grid-template-columns: minmax(0, 1fr) 36px 36px 36px;
  gap: 2px 8px;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--ink);
  width: 100%;
}

.heatmap__loading {
  grid-column: 1 / -1;
  margin: 0;
  color: var(--ink-faint);
  font-style: italic;
  font-family: var(--font-body);
  padding: 1rem 0;
  text-align: center;
}

.heatmap__header {
  display: contents;
}
.heatmap__header > * {
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-soft);
  padding-bottom: 6px;
  border-bottom: 1px solid var(--paper-edge);
  text-align: center;
}
.heatmap__header > .heatmap__corner {
  text-align: left;
}

.heatmap__tissue {
  text-align: left;
  padding: 3px 0;
  color: var(--ink);
  letter-spacing: 0.02em;
  /* Wrap long tissue names gracefully */
  overflow-wrap: anywhere;
}

.heatmap__cell {
  width: 100%;
  height: 22px;
  border-radius: 2px;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.04em;
  border: 1px solid transparent;
  background: var(--paper-edge);
  color: var(--ink-faint);
}

/* Four expression-level steps mapped onto a single warm ramp */
.heatmap__cell[data-level="high"] {
  background: var(--heat-41);
  color: var(--paper);
  font-weight: 600;
}
.heatmap__cell[data-level="medium"] {
  background: var(--heat-40);
  color: var(--paper);
}
.heatmap__cell[data-level="low"] {
  background: #e8c896;
  color: var(--ink-soft);
}
.heatmap__cell[data-level="not detected"] {
  background: var(--paper);
  color: var(--ink-faint);
  border: 1px dashed var(--paper-edge);
}
.heatmap__cell[data-level="n/a"] {
  background: transparent;
  color: var(--ink-faint);
}

.heatmap__group-break {
  grid-column: 1 / -1;
  border-top: 1px dashed var(--paper-edge);
  margin-top: 6px;
  padding-top: 2px;
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.heatmap-caption {
  margin: 12px 0 0 0;
  font-family: var(--font-body);
  font-size: 0.78rem;
  font-style: italic;
  color: var(--ink-soft);
  text-align: center;
}

/* ---------- Chapter 6: ClinVar variant cards ---------- */

.chapter--variants .chapter__inner--variants {
  /* Top section: marginalia + reading body only (no figure column).
     Variant grid sits as a full-width block beneath. */
  grid-template-columns: 1fr;
}

@media (min-width: 1024px) {
  .chapter--variants .chapter__inner--variants {
    grid-template-columns: 20% minmax(0, 60%);
    justify-content: start;
  }
}

.ch6-warning {
  margin: 1.5rem 0 0 0;
  padding: 14px 18px;
  background: rgba(178, 58, 31, 0.08);
  border-left: 3px solid var(--heat-41);
  font-family: var(--font-body);
  font-size: 0.95rem;
  color: var(--ink);
  font-style: italic;
}

.variant-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
  margin: 32px auto 0;
  max-width: 1440px;
  padding: 0 var(--gutter);
}

@media (min-width: 720px) {
  .variant-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}
@media (min-width: 1100px) {
  .variant-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.variant-grid__loading {
  grid-column: 1 / -1;
  text-align: center;
  color: var(--ink-faint);
  font-style: italic;
  padding: 2rem 0;
}

.variant-card {
  background: var(--surface-card);
  border: 1px solid var(--paper-edge);
  border-radius: 4px;
  padding: 14px 16px 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-size: 0.85rem;
  line-height: 1.4;
}

.variant-card__row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 10px;
}

.variant-card__gene {
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--ink);
}

.variant-card__pill {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 3px 9px;
  border-radius: 2px;
  background: var(--paper-edge);
  color: var(--ink-soft);
  white-space: nowrap;
}

.variant-card__pill[data-sig="pathogenic"] {
  background: var(--heat-42);
  color: var(--paper);
}
.variant-card__pill[data-sig="likely-pathogenic"] {
  background: var(--heat-41);
  color: var(--paper);
}
.variant-card__pill[data-sig="vus"] {
  background: var(--heat-39);
  color: var(--ink);
}
.variant-card__pill[data-sig="benign"] {
  background: var(--heat-37);
  color: var(--paper);
}
.variant-card__pill[data-sig="conflicting"] {
  background: var(--ink-faint);
  color: var(--paper);
}

.variant-card__hgvs {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--ink);
  word-break: break-word;
  overflow-wrap: anywhere;
}

.variant-card__protein {
  font-family: var(--font-mono);
  color: var(--ink-soft);
  font-size: 0.8rem;
}

.variant-card__coord {
  font-family: var(--font-mono);
  color: var(--ink-faint);
  font-size: 0.75rem;
}

.variant-card__stars {
  display: flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--ink-faint);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.variant-card__stars-glyph {
  letter-spacing: 0.1em;
  color: var(--heat-39);
  font-size: 0.9rem;
}

.variant-card__citations {
  font-size: 0.78rem;
  color: var(--ink-soft);
  display: flex;
  flex-wrap: wrap;
  gap: 4px 8px;
  align-items: baseline;
}
.variant-card__citations-label {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.variant-card__link {
  margin-top: auto;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--accent-link);
}

/* ---------- Chapter 7: Reactome full-bleed pathway ---------- */

.chapter--pathway {
  /* Override the 3-column shell: this chapter is figure-first. */
  display: block;
  padding-top: var(--section-gap-y);
  padding-bottom: var(--section-gap-y);
}

.chapter--pathway__head {
  max-width: 80ch;
  margin: 0 auto 32px;
  text-align: center;
}

.chapter__title--centered {
  text-align: center;
}

.pathway-fullbleed {
  margin: 0 auto;
  max-width: 1440px;
  padding: 0;
  width: 100%;
}

.pathway-card-fullbleed {
  background: var(--paper);
  border: 1px solid var(--paper-edge);
  border-radius: 4px;
  padding: 8px;
  box-shadow: 0 12px 36px -16px rgba(34, 26, 21, 0.25),
    0 1px 0 var(--paper-edge);
  overflow: auto;            /* horizontal scroll on small screens */
  -webkit-overflow-scrolling: touch;
  transition: box-shadow 0.18s ease, outline 0.18s ease;
}

.pathway-card-fullbleed--hover {
  outline: 2px solid var(--heat-39, #C9A95C);
  outline-offset: 4px;
  box-shadow: 0 12px 36px -10px rgba(34, 26, 21, 0.35),
    0 1px 0 var(--paper-edge);
}

/* Hint on mobile that the diagram scrolls horizontally inside its card. */
@media (max-width: 720px) {
  .pathway-card-fullbleed::after {
    content: "↔ swipe to see the full diagram";
    display: block;
    text-align: center;
    font-family: var(--font-mono);
    font-size: 0.7rem;
    letter-spacing: 0.08em;
    color: var(--ink-soft);
    padding: 4px 0 0;
  }
}

/* Universal keyboard-focus ring on interactive elements without one. */
a:focus-visible,
button:focus-visible,
[role="button"]:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  outline: 2px solid var(--heat-39);
  outline-offset: 2px;
}

.pathway-image,
.pathway-svg-inline {
  display: block;
  width: 100%;
  height: auto;
  min-width: 720px;          /* keep labels legible; user scrolls horizontally if narrower */
  max-width: 100%;
  background: var(--paper);
}

/* Jump-nav chips below the pathway diagram */
.pathway-jumpnav {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 0.75rem;
  justify-content: center;
  max-width: 80ch;
  margin: 16px auto 0;
  padding: 0 var(--gutter);
  font-family: var(--font-body);
  font-size: 0.85rem;
  color: var(--ink-soft);
}

.pathway-jumpnav__label {
  font-style: italic;
}

.pathway-chip {
  display: inline-flex;
  align-items: baseline;
  gap: 0.35rem;
  padding: 0.25rem 0.65rem;
  background: color-mix(in srgb, var(--ink) 6%, var(--paper));
  border: 1px solid var(--paper-edge);
  border-radius: 999px;
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  text-decoration: none;
  transition: background 0.14s ease, border-color 0.14s ease;
}
.pathway-chip:hover,
.pathway-chip:focus-visible {
  background: color-mix(in srgb, var(--ink) 14%, var(--paper));
  border-color: var(--ink);
  outline: none;
}
.pathway-chip__hint {
  font-size: 0.72rem;
  color: var(--ink-soft);
  letter-spacing: 0.04em;
}

@media (min-width: 720px) {
  .pathway-image {
    min-width: 0;
  }
}

.pathway-fullbleed-caption {
  margin: 14px auto 0;
  max-width: 80ch;
  text-align: center;
  font-family: var(--font-body);
  font-size: 0.82rem;
  font-style: italic;
  color: var(--ink-soft);
  line-height: 1.5;
  padding: 0 var(--gutter);
}

.chapter--pathway__body {
  margin-top: 40px;
}

.chapter--pathway__body .chapter__inner {
  grid-template-columns: 1fr;
  justify-items: center;
}

.reading--pathway {
  max-width: var(--reading-max);
}

/* ---------- Chapter 8: WBGT -> core temperature bridge ---------- */

.chapter--bridge {
  display: block;
  padding-top: var(--section-gap-y);
  padding-bottom: var(--section-gap-y);
}

.chapter__inner--bridge {
  grid-template-columns: 1fr;
  max-width: 1200px;
  margin: 0 auto;
}

.bridge-head {
  max-width: 80ch;
  margin: 0 auto 32px;
  text-align: center;
}

.bridge-intro {
  margin: 0 auto 1rem;
  max-width: var(--reading-max);
  text-align: left;
}

.ch8-warning {
  margin: 1rem auto 0;
  max-width: var(--reading-max);
  padding: 12px 16px;
  background: rgba(178, 58, 31, 0.08);
  border-left: 3px solid var(--heat-41);
  font-family: var(--font-body);
  font-size: 0.95rem;
  color: var(--ink);
  font-style: italic;
  text-align: left;
}

.bridge-pane {
  display: grid;
  grid-template-columns: 1fr;
  gap: 32px;
  margin-top: 24px;
}

@media (min-width: 880px) {
  .bridge-pane {
    grid-template-columns: minmax(0, 320px) minmax(0, 1fr);
    align-items: start;
  }
}

.bridge-controls {
  background: var(--surface-card);
  border: 1px solid var(--paper-edge);
  border-radius: 4px;
  padding: 16px 18px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.bridge-input {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: baseline;
  gap: 4px 8px;
}

.bridge-input label {
  grid-column: 1 / -1;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

.bridge-input input[type="range"] {
  width: 100%;
  grid-column: 1 / 2;
  accent-color: var(--heat-41);
  min-height: 44px; /* meet WCAG 2.5.5 / mobile touch target */
}

.bridge-input output {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--ink);
  text-align: right;
  min-width: 3.5em;
}

.bridge-input select {
  grid-column: 1 / -1;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  padding: 10px 12px;
  min-height: 44px; /* meet WCAG 2.5.5 / mobile touch target */
  background: var(--paper);
  border: 1px solid var(--paper-edge);
  border-radius: 2px;
  color: var(--ink);
}

.bridge-readout {
  border-top: 1px dashed var(--paper-edge);
  margin: 4px 0 0 0;
  padding-top: 10px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.bridge-readout__label {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.bridge-readout__value {
  font-family: var(--font-display);
  font-size: 1.85rem;
  line-height: 1;
  color: var(--ink);
  font-variant-numeric: tabular-nums;
}

.bridge-state {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-soft);
  font-style: italic;
}

.bridge-state[data-strain="extreme"] {
  color: var(--heat-42);
  font-weight: 600;
  font-style: normal;
}

.bridge-state[data-strain="high"] {
  color: var(--heat-41);
}

.bridge-chart-wrap {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.bridge-chart {
  width: 100%;
  height: auto;
  background: var(--surface-card);
  border: 1px solid var(--paper-edge);
  border-radius: 4px;
}

.bridge-chart-caption {
  margin: 0;
  font-family: var(--font-body);
  font-size: 0.78rem;
  color: var(--ink-soft);
  font-style: italic;
  text-align: center;
}

.bridge-chart .axis-line {
  stroke: var(--rule);
  stroke-width: 1;
}
.bridge-chart .axis-label {
  font-family: var(--font-mono);
  font-size: 9px;
  letter-spacing: 0.04em;
  fill: var(--ink-soft);
}
.bridge-chart .threshold-line {
  stroke: var(--ink-faint);
  stroke-width: 1;
  stroke-dasharray: 4 4;
}
.bridge-chart .threshold-label {
  font-family: var(--font-mono);
  font-size: 9px;
  fill: var(--ink-faint);
}
.bridge-chart .curve {
  fill: none;
  stroke: var(--heat-41);
  stroke-width: 2.5;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.bridge-chart .crossing-dot {
  fill: var(--heat-42);
  stroke: var(--paper);
  stroke-width: 1.5;
}

.colophon-extra {
  margin-top: 64px;
  padding-top: 32px;
  border-top: 1px solid var(--paper-edge);
}

.chapter--bridge .colophon-extra .chapter__inner {
  grid-template-columns: 1fr;
  justify-items: center;
}

.reading--colophon {
  max-width: var(--reading-max);
  text-align: center;
}

/* ---------- Pathway snippet (Ch 3 mini-Reactome) ---------- */

.pathway-snippet {
  margin: 0;
  width: 100%;
  max-width: 360px;
  background: var(--surface-card);
  border: 1px solid var(--paper-edge);
  border-radius: 4px;
  padding: 12px 16px 12px;
}

.pathway-svg {
  display: block;
  width: 100%;
  height: auto;
  margin: 0 auto;
}

.pathway-label {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.04em;
  fill: var(--ink);
}

.pathway-label--inverted {
  fill: var(--paper);
  font-weight: 600;
}

.pathway-sublabel {
  font-family: var(--font-mono);
  font-size: 8px;
  letter-spacing: 0.04em;
  fill: var(--ink-faint);
}

.pathway-caption {
  margin: 8px 0 0 0;
  font-family: var(--font-body);
  font-size: 0.78rem;
  line-height: 1.45;
  color: var(--ink-soft);
  font-style: italic;
}

.pathway-caption .mono {
  font-style: normal;
  font-size: 0.85em;
  color: var(--ink);
}

/* ---------- Protein viewer card ---------- */

.viewer-card {
  margin: 0;
  width: 100%;
  max-width: 360px;
  background: var(--surface-viewer);
  border-radius: 4px;
  overflow: hidden;
  box-shadow: 0 6px 24px -8px rgba(34, 26, 21, 0.25),
    0 1px 0 var(--paper-edge);
  transition: box-shadow 240ms cubic-bezier(0.4, 0, 0.2, 1),
    transform 240ms cubic-bezier(0.4, 0, 0.2, 1);
}

.viewer-card:hover {
  box-shadow: 0 10px 32px -8px rgba(34, 26, 21, 0.32),
    0 1px 0 var(--paper-edge);
  transform: translateY(-1px);
}

.viewer {
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
  background: var(--surface-viewer);
  overflow: hidden;
}

.viewer canvas {
  display: block;
}

.viewer__loading {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: #d9d2bb;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  pointer-events: none;
}

.viewer-card__caption {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 8px 12px;
  background: var(--surface-viewer);
  color: #d9d2bb;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.04em;
}

.viewer-card__pdb-link {
  color: #d9d2bb;
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 160ms ease, color 160ms ease;
}
.viewer-card__pdb-link:hover,
.viewer-card__pdb-link:focus-visible {
  color: #f5efdf;
  border-bottom-color: #d9d2bb;
}

.viewer-card__source {
  color: #8d8674;
}

/* ---------- Citation block ---------- */

.citations {
  margin-top: 2rem;
  border-top: 1px solid var(--paper-edge);
  padding-top: 1rem;
}

.citations > summary {
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  letter-spacing: 0.04em;
  color: var(--ink-soft);
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.citations > summary::after {
  content: "▾";
  color: var(--ink-faint);
  font-size: 0.9em;
  display: inline-block;
  transition: transform 240ms cubic-bezier(0.4, 0, 0.2, 1);
}

.citations[open] > summary::after {
  transform: rotate(180deg);
}

.citations__list {
  list-style: none;
  padding: 1rem 0 0 0;
  margin: 0;
}

.citations__list li {
  padding: 0.85rem 0;
  border-top: 1px solid var(--paper-edge);
  font-size: 0.95rem;
  line-height: 1.55;
}

.citations__list li:first-child {
  border-top: 0;
}

.citation__authors {
  font-style: italic;
  color: var(--ink-soft);
}
.citation__title {
  font-style: italic;
  color: var(--ink);
}
.citation__journal {
  font-variant-caps: small-caps;
  letter-spacing: 0.03em;
  color: var(--ink-soft);
}
.citation__pmid {
  font-family: var(--font-mono);
  font-size: 0.85em;
  margin-left: 0.5em;
}

.citations__loading {
  color: var(--ink-faint);
  font-style: italic;
}

.citations__error {
  color: var(--heat-41);
  font-family: var(--font-mono);
  font-size: 0.85em;
}

/* ---------- Footer / colophon ---------- */

.colophon {
  padding: 2rem var(--gutter) 3rem;
  border-top: 1px solid var(--paper-edge);
  color: var(--ink-faint);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  text-align: center;
}

.colophon p {
  margin: 0.5rem 0;
}

/* ---------- Stub chapter styling (distinguishable from Ch 1) ---------- */

.chapter--stub {
  min-height: 60vh;
}

.chapter--stub .chapter__title {
  font-size: clamp(1.5rem, 1rem + 1.5vw, 2rem);
  color: var(--ink-soft);
}