/* Causality design tokens: one palette for every page. Stage hues follow the causal roadmap. */
:root {
  --bg: #ffffff;
  --paper: #ffffff;
  --panel: var(--paper);
  --ink: #1b2530;
  --muted: #5d6b78;
  --rule: #d3dae1;
  --grid: #e6ebf0;
  --soft: #eef2f6;
  --p: #2b4bc8;
  --or: #e0801a;
  --teal: #1c8c8c;
  --green: #3d9440;
  --purple: #6a3fb5;
  --red: #c6362c;
  --phat: #b0287f;
  --pen: #1b2530;
  --s-question: #2b4bc8;
  --s-identification: #1c8c8c;
  --s-model: #6a3fb5;
  --s-estimation: #e0801a;
  --s-uncertainty: #b0287f;
  --s-interpretation: #3d9440;
  --stage: var(--purple);
  --water: #dce3ea;
  --shadow:
    0 1px 2px rgba(27, 37, 48, 0.06), 0 8px 24px -12px rgba(27, 37, 48, 0.18);
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #12181f;
    --paper: #1b232c;
    --ink: #e7ebef;
    --muted: #9aa8b5;
    --rule: #33404c;
    --grid: #28323c;
    --soft: #222c36;
    --p: #8aa0f0;
    --or: #f2a353;
    --teal: #5cc4c4;
    --green: #7ccb7c;
    --purple: #a98be6;
    --red: #ef7a70;
    --phat: #e36ab8;
    --pen: #e7ebef;
    --s-question: #8aa0f0;
    --s-identification: #5cc4c4;
    --s-model: #a98be6;
    --s-estimation: #f2a353;
    --s-uncertainty: #e36ab8;
    --s-interpretation: #7ccb7c;
    --water: #232d38;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 8px 24px -12px rgba(0, 0, 0, 0.6);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #12181f;
  --paper: #1b232c;
  --ink: #e7ebef;
  --muted: #9aa8b5;
  --rule: #33404c;
  --grid: #28323c;
  --soft: #222c36;
  --p: #8aa0f0;
  --or: #f2a353;
  --teal: #5cc4c4;
  --green: #7ccb7c;
  --purple: #a98be6;
  --red: #ef7a70;
  --phat: #e36ab8;
  --pen: #e7ebef;
  --s-question: #8aa0f0;
  --s-identification: #5cc4c4;
  --s-model: #a98be6;
  --s-estimation: #f2a353;
  --s-uncertainty: #e36ab8;
  --s-interpretation: #7ccb7c;
  --water: #232d38;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 8px 24px -12px rgba(0, 0, 0, 0.6);
  color-scheme: dark;
}
* {
  box-sizing: border-box;
}
body {
  margin: 0;
  padding: 36px 20px 64px;
  background: var(--bg);
  color: var(--ink);
  font-family: "IBM Plex Sans", system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.55;
}
.wrap {
  max-width: 1080px;
  margin: auto;
}
h1,
h2,
h3 {
  font-family: "Fraunces", Georgia, serif;
  font-weight: 600;
  line-height: 1.15;
  text-wrap: balance;
}
h1 {
  font-size: clamp(34px, 4.2vw, 44px);
  letter-spacing: -0.012em;
  line-height: 1.06;
  max-width: 24ch;
  margin: 8px 0 12px;
}
h2 {
  font-size: 26px;
  margin-top: 46px;
}
h3 {
  font-size: 20px;
}
.eyebrow {
  font-family: "IBM Plex Mono", monospace;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 12px;
  color: var(--muted);
}
p {
  max-width: 72ch;
}
.lede {
  font-size: 17.5px;
  color: var(--muted);
  max-width: 60ch;
  margin-bottom: 30px;
}
a {
  color: var(--p);
}
button,
input,
select,
textarea {
  font: inherit;
}
button,
.course-btn {
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 7px;
  color: var(--ink);
  padding: 9px 14px;
  cursor: pointer;
}
button.primary {
  background: var(--purple);
  border-color: var(--purple);
  color: #fff;
}
button:hover {
  border-color: var(--purple);
}
button:disabled {
  opacity: 0.6;
  cursor: default;
}
:focus-visible {
  outline: 3px solid var(--purple);
  outline-offset: 3px;
}
input,
select,
textarea {
  max-width: 100%;
  color: var(--ink);
  background: var(--paper);
  border: 1px solid var(--rule);
  padding: 8px;
  border-radius: 5px;
}
input[type="range"] {
  padding: 0;
  accent-color: var(--purple);
  width: 100%;
}
label {
  display: grid;
  gap: 6px;
  margin: 14px 0;
}
.btns {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 14px 0;
}
.lab-step,
.lab-card,
.practice {
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 14px;
  padding: clamp(16px, 3vw, 30px);
  margin: 22px 0;
}
.lab-step h2,
.practice h2 {
  margin-top: 8px;
}
.lab-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.55fr) minmax(240px, 1fr);
  gap: 28px;
}
.lab-grid > * {
  min-width: 0;
}
svg {
  width: 100%;
  height: auto;
  display: block;
  overflow: visible;
}
svg text {
  fill: var(--ink);
  font:
    14px system-ui,
    sans-serif;
}
.axis {
  stroke: var(--muted);
  stroke-width: 1;
  fill: none;
}
.math {
  font:
    16px/1.9 ui-monospace,
    monospace;
  border-left: 3px solid var(--purple);
  padding: 12px 16px;
  background: var(--soft);
  overflow-wrap: anywhere;
}
.note,
.caption {
  font-size: 14px;
  color: var(--muted);
}
.readout {
  font-variant-numeric: tabular-nums;
}
.readout strong {
  font-size: 25px;
  font-weight: 500;
  color: var(--purple);
}
table {
  border-collapse: collapse;
  width: 100%;
  font-size: 15px;
}
caption {
  text-align: left;
  font-weight: 600;
  padding: 8px 0;
}
th,
td {
  text-align: right;
  padding: 8px;
  border-bottom: 1px solid var(--rule);
}
th:first-child,
td:first-child {
  text-align: left;
}
.table-wrap {
  max-width: 100%;
  overflow-x: auto;
}
.legend {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
  font-size: 14px;
}
.legend-swatches span {
  display: inline-flex;
  align-items: center;
  gap: 7px;
}
.legend svg.swatch {
  flex: none;
  display: inline-block;
  width: 28px;
  height: 10px;
  margin: 0;
  border: 0;
  background: none;
}
.pill {
  padding: 3px 10px;
  background: var(--soft);
  border-radius: 20px;
}
.step-nav {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin: 20px 0;
}
.step-nav button[aria-current="step"] {
  border: 2px solid var(--purple);
}
.symbol {
  color: var(--purple);
  font-family: ui-monospace, monospace;
}
.bar-mass {
  display: grid;
  grid-template-columns: 60px 1fr 70px;
  gap: 12px;
  align-items: center;
  margin: 12px 0;
}
.mass-track {
  height: 28px;
  background: var(--grid);
  border-radius: 4px;
}
.mass-fill {
  height: 100%;
  background: var(--teal);
  border-radius: 4px;
}
.lab-step[hidden] {
  display: none;
}
.geometry-controls {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 20px;
}
.geometry-figure {
  touch-action: pan-y;
  cursor: grab;
  background: var(--soft);
  border-radius: 12px;
}
.geometry-figure:active {
  cursor: grabbing;
}
.warning {
  border-left: 3px solid var(--or);
  padding: 10px 14px;
  background: var(--soft);
}
.road-list {
  padding-left: 22px;
}
.road-list li {
  margin: 15px 0;
}
.formula-details {
  margin: 20px 0;
}
.sources {
  font-size: 14px;
  margin-top: 32px;
}
.hist-bars {
  display: flex;
  align-items: end;
  gap: 2px;
  height: 190px;
  border-bottom: 1px solid var(--muted);
  margin: 12px 0;
}
.hist-bin {
  flex: 1;
  background: var(--purple);
  min-height: 1px;
}
.metric-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}
.metric-grid div {
  background: var(--soft);
  padding: 14px;
  border-radius: 8px;
}
.metric-grid b {
  display: block;
  font-size: 24px;
}
.hub-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 16px;
}
.unit-card {
  border: 1px solid var(--rule);
  border-radius: 12px;
  padding: 20px;
  background: var(--paper);
}
.unit-card h3 {
  margin: 10px 0;
}
.unit-card p {
  font-size: 15px;
}
.hero-links {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}
.status {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--teal);
}
.glossary-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 16px;
}
.glossary-grid > div {
  padding: 20px;
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 10px;
}
.glossary-grid dt {
  font-size: 23px;
  color: var(--purple);
}
.glossary-grid dd {
  margin: 10px 0;
}
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}
@media (max-width: 760px) {
  .lab-grid {
    grid-template-columns: 1fr;
  }
  .metric-grid {
    grid-template-columns: 1fr;
  }
  .lab-step {
    padding: 16px;
  }
  body {
    font-size: 16px;
    padding: 36px 16px 50px;
  }
  svg text {
    font-size: 18px;
  }
  .geometry-controls {
    grid-template-columns: 1fr;
  }
  th,
  td {
    padding: 6px;
  }
  .course-bar {
    margin-left: -16px !important;
    margin-right: -16px !important;
  }
  h2 {
    font-size: 26px;
  }
}
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation: none !important;
    transition: none !important;
  }
}
@media (max-width: 760px) {
  svg text {
    font-size: 27px;
  }
  #dag text {
    font-size: 22px;
  }
  .geometry-figure {
    overflow: hidden;
  }
}

/* Figure kit (shared/anim.js) */
svg.fig {
  width: 100%;
  height: auto;
  display: block;
  font-family: "IBM Plex Sans", system-ui, sans-serif;
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 8px;
}
svg.fig .grid {
  stroke: var(--grid);
  stroke-width: 1;
}
svg.fig .axis {
  stroke: var(--muted);
  stroke-width: 1.2;
}
svg.fig .tick,
svg.fig .ref-label,
svg.fig .fig-text {
  font-family: "IBM Plex Mono", monospace;
  font-size: 11.5px;
}
svg.fig .tick,
svg.fig .ref-label:not([fill]),
svg.fig .fig-text:not([fill]) {
  fill: var(--muted);
}
svg.fig .axis-label {
  font-family: "Fraunces", Georgia, serif;
  font-style: italic;
  font-size: 13.5px;
  fill: var(--ink);
}
svg.fig .fig-text.ink:not([fill]) {
  fill: var(--ink);
  font-family: "IBM Plex Sans", system-ui, sans-serif;
  font-size: 13px;
}
svg.fig .mark-line {
  stroke-width: 2.5;
  stroke-linejoin: round;
  stroke-linecap: round;
}
svg.fig .mark-ref {
  stroke-width: 1.5;
  stroke-dasharray: 5 4;
}
.fig-player {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  margin: 10px 0 6px;
}
.fig-player label {
  display: flex;
  align-items: center;
  gap: 8px;
  flex: 1;
  min-width: 180px;
  margin: 0;
  font-size: 13px;
  color: var(--muted);
}
.fig-player label input {
  flex: 1;
}
.fig-player .v {
  font-family: "IBM Plex Mono", monospace;
  color: var(--ink);
  min-width: 3ch;
}
.figure {
  margin: 14px 0 18px;
}
.figure .fig-caption {
  font-size: 14px;
  color: var(--muted);
  margin: 8px 0 0;
  min-height: 2.6em;
}
.figure .fig-readout {
  font-family: "IBM Plex Mono", monospace;
  font-size: 13px;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 4px 12px;
  margin-top: 8px;
  font-variant-numeric: tabular-nums;
}
.figure .fig-readout .k {
  color: var(--muted);
}
.figure .fig-controls {
  display: grid;
  gap: 8px;
  margin-top: 8px;
}
.figure .fig-controls label {
  margin: 0;
  font-size: 13.5px;
}
.figure .fig-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 280px;
  gap: 16px;
  align-items: start;
}
@media (max-width: 900px) {
  .figure .fig-row {
    grid-template-columns: 1fr;
  }
}

.variance-bar {
  display: flex;
  height: 12px;
  border-radius: 6px;
  background: var(--grid);
  overflow: hidden;
  margin: 8px 0 4px;
}
.variance-bar i {
  display: block;
  height: 100%;
  transition: width 0.1s linear;
}
.variance-bar .kept {
  background: var(--purple);
}
.variance-bar .lost {
  background: var(--or);
}
.variance-bar.over {
  box-shadow: 0 0 0 2px var(--red);
}

/* Phones: the viewBox scales to ~55%, so text set in viewBox units grows to stay legible. */
@media (max-width: 720px) {
  svg.fig.fig-wide .tick,
  svg.fig.fig-wide .ref-label,
  svg.fig.fig-wide .fig-text {
    font-size: 17px;
  }
  svg.fig.fig-wide .fig-text.ink {
    font-size: 19px;
  }
  svg.fig.fig-wide .axis-label {
    font-size: 20px;
  }
}