:root {
  color-scheme: dark;
  --bg: #080f1a;
  --panel: #101b2c;
  --ink: #e6eef9;
  --muted: #a8bad1;
  --accent: #51d2b7;
  --edge: #273850;
  font-family:
    Inter,
    system-ui,
    -apple-system,
    sans-serif;
}
* {
  box-sizing: border-box;
}
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.55;
}
a {
  color: var(--accent);
}
button,
input,
select {
  font: inherit;
}
button,
.file-button {
  border: 1px solid var(--edge);
  background: #17263b;
  color: var(--ink);
  border-radius: 5px;
  padding: 7px 12px;
  cursor: pointer;
}
button:hover,
.file-button:hover {
  border-color: var(--accent);
}
button:disabled {
  opacity: 0.45;
  cursor: wait;
}
button:focus-visible,
a:focus-visible,
input:focus-visible,
select:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}
input,
select {
  accent-color: var(--accent);
  min-width: 0;
}
select,
input[type="number"] {
  background: var(--bg);
  color: var(--ink);
  border: 1px solid var(--edge);
  border-radius: 4px;
  padding: 5px;
  max-width: 100%;
}
.skip {
  position: absolute;
  top: -60px;
}
.skip:focus {
  top: 0;
  background: var(--bg);
  z-index: 5;
}
.masthead {
  display: flex;
  align-items: center;
  gap: 25px;
  padding: 17px 28px;
  border-bottom: 1px solid var(--edge);
  font-size: 11px;
  letter-spacing: 0.13em;
}
.masthead a {
  text-decoration: none;
}
.masthead span {
  color: var(--muted);
  flex: 1;
}
.layout {
  display: grid;
  grid-template-columns: 248px minmax(0, 1fr);
  max-width: 1800px;
  margin: auto;
}
nav {
  padding: 25px 16px;
  max-height: calc(100vh - 54px);
  overflow: auto;
  position: sticky;
  top: 0;
  border-right: 1px solid var(--edge);
}
nav details {
  margin-bottom: 22px;
}
nav summary {
  font-size: 11px;
  letter-spacing: 0.05em;
  color: var(--muted);
  cursor: pointer;
  margin-bottom: 8px;
}
nav a {
  display: block;
  text-decoration: none;
  font-size: 12px;
  line-height: 1.4;
  padding: 8px 9px;
  color: var(--muted);
  border-left: 2px solid transparent;
}
nav a span {
  display: block;
  font-size: 10px;
  color: #738baa;
}
nav a[aria-current="page"] {
  border-color: var(--accent);
  background: #112a31;
  color: var(--ink);
}
main {
  min-width: 0;
  padding: 30px clamp(16px, 3vw, 48px) 50px;
}
.eyebrow {
  font-size: 11px;
  letter-spacing: 0.13em;
  color: var(--accent);
}
h1 {
  font-weight: 530;
  letter-spacing: -0.035em;
  font-size: clamp(26px, 3vw, 42px);
  line-height: 1.14;
  margin: 10px 0 16px;
  max-width: 1000px;
}
.question {
  font-size: 18px;
  color: var(--muted);
  margin: 0 0 24px;
}
.prediction {
  display: flex;
  gap: 22px;
  border-top: 1px solid var(--edge);
  border-bottom: 1px solid var(--edge);
  padding: 16px 0;
  margin-bottom: 24px;
}
.prediction span {
  font-size: 10px;
  letter-spacing: 0.13em;
  color: var(--accent);
  white-space: nowrap;
  padding-top: 4px;
}
.prediction p {
  margin: 0;
  max-width: 900px;
}
#controls,
.control-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px 24px;
}
.control {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 5px 8px;
  font-size: 12px;
  color: var(--muted);
}
.control > span {
  grid-column: 1/-1;
}
.control select {
  grid-column: 1/-1;
}
.control output {
  font-variant-numeric: tabular-nums;
  font-size: 12px;
}
.advanced {
  grid-column: 1/-1;
  margin-bottom: 0 !important;
}
.advanced summary {
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 12px;
}
.toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 22px 0;
}
.toolbar #run {
  background: var(--accent);
  border-color: var(--accent);
  color: #081b20;
  font-weight: 650;
  min-width: 70px;
}
.seed {
  font-size: 12px;
  color: var(--muted);
  display: flex;
  align-items: center;
  gap: 6px;
  margin-left: 8px;
}
.seed input {
  width: 105px;
}
#status {
  font-size: 11px;
  color: var(--muted);
  margin-left: auto;
  font-variant-numeric: tabular-nums;
}
.metrics {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 28px;
  border-top: 1px solid var(--edge);
  padding: 17px 0 22px;
}
.metrics span {
  display: block;
  font-size: 11px;
  color: var(--muted);
}
.metrics strong {
  font-size: 22px;
  font-weight: 450;
  font-variant-numeric: tabular-nums;
}
.metrics small {
  font-size: 11px;
  color: var(--muted);
  margin-left: 5px;
}
.charts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}
.chart {
  min-width: 0;
  background: var(--panel);
  border: 1px solid var(--edge);
  padding: 12px 8px 10px;
  border-radius: 6px;
}
.chart-heading {
  display: flex;
  align-items: start;
  gap: 10px;
  padding: 0 8px;
}
.chart h2 {
  font-size: 13px;
  font-weight: 550;
  line-height: 1.4;
  flex: 1;
  margin: 0;
}
.svg-export {
  font-size: 10px;
  padding: 2px 6px;
}
.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 5px 14px;
  padding: 0 12px;
  font-size: 10px;
  color: var(--muted);
}
.legend span {
  display: flex;
  align-items: center;
  gap: 5px;
}
.legend i {
  display: inline-block;
  width: 16px;
  height: 3px;
}
.timeline {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 20px 0;
  font-size: 11px;
  color: var(--muted);
}
.timeline input {
  flex: 1;
}
.timeline output {
  min-width: 90px;
  font-variant-numeric: tabular-nums;
}
.timeline button {
  font-size: 11px;
}
.observation {
  border-left: 2px solid var(--accent);
  padding-left: 16px;
  font-size: 14px;
  color: var(--muted);
}
details {
  margin-bottom: 18px;
}
summary {
  cursor: pointer;
}
#explanation {
  font-size: 14px;
  max-width: 950px;
  color: var(--muted);
}
.table-scroll {
  max-height: 330px;
  overflow: auto;
}
table {
  border-collapse: collapse;
  font-size: 12px;
  width: 100%;
  font-variant-numeric: tabular-nums;
}
td,
th {
  padding: 6px 12px;
  text-align: left;
  border-bottom: 1px solid var(--edge);
}
th {
  position: sticky;
  top: 0;
  background: var(--panel);
}
.exports {
  display: flex;
  flex-wrap: wrap;
  gap: 9px;
  font-size: 12px;
}
.file-button input {
  display: none;
}
.footnote {
  font-size: 11px;
  color: #8298b6;
  max-width: 850px;
}
#error {
  padding: 16px;
  background: #3b2025;
  border: 1px solid #a55a66;
  margin-bottom: 20px;
}
.embedded nav {
  display: none;
}
.embedded .layout {
  grid-template-columns: 1fr;
}
.embedded .masthead {
  padding: 9px 16px;
}
.embedded .masthead span {
  display: none;
}
.embedded main {
  padding: 20px;
}
.embedded h1 {
  font-size: 28px;
}
.embedded .exports {
  margin-top: 16px;
}
@media (min-width: 1500px) {
  .charts {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}
@media (max-width: 1050px) {
  .layout {
    grid-template-columns: 205px minmax(0, 1fr);
  }
  .charts {
    grid-template-columns: 1fr;
  }
  #controls,
  .control-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .masthead span {
    display: none;
  }
  .masthead a:last-child {
    margin-left: auto;
  }
}
@media (max-width: 700px) {
  .layout {
    display: block;
  }
  nav {
    position: static;
    max-height: 210px;
    border-right: 0;
    border-bottom: 1px solid var(--edge);
    padding: 12px 16px;
  }
  nav details {
    margin: 0 0 10px;
  }
  nav a {
    padding: 5px 10px;
  }
  main {
    padding: 23px 14px;
  }
  .masthead {
    padding: 12px 14px;
    gap: 12px;
    font-size: 9px;
  }
  .prediction {
    gap: 12px;
    font-size: 14px;
  }
  .question {
    font-size: 16px;
  }
  #controls,
  .control-grid {
    grid-template-columns: 1fr 1fr;
    gap: 12px;
  }
  .toolbar {
    gap: 6px;
  }
  #status {
    flex-basis: 100%;
    margin: 4px 0;
  }
  .metrics {
    gap: 10px 20px;
  }
  .metrics strong {
    font-size: 20px;
  }
  .timeline {
    gap: 7px;
  }
  .timeline label {
    max-width: 52px;
  }
  .timeline output {
    min-width: 67px;
  }
  .chart {
    padding: 10px 2px;
  }
  .embedded main {
    padding: 16px 10px;
  }
}
@media (prefers-reduced-motion: reduce) {
  * {
    scroll-behavior: auto;
  }
}

/* The surrounding lecture supplies the title; keep the embedded plots close. */
.embedded .masthead,
.embedded h1 {
  display: none;
}
.embedded .eyebrow {
  margin-bottom: 10px;
}
.embedded .prediction {
  margin-bottom: 16px;
  padding: 12px 0;
}
.embedded .toolbar {
  margin: 16px 0;
}

.scene {
  margin: 1rem 0;
}
.scene[hidden] {
  display: none;
}
.scene-controls {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  align-items: center;
  padding: 0.6rem 0;
}
.scene-controls label {
  display: flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.85rem;
}
.scene-controls select {
  max-width: 17rem;
}
.scene-viewport {
  touch-action: none;
  cursor: grab;
}
.scene-viewport:active {
  cursor: grabbing;
}
.scene-viewport:focus-visible {
  outline: 2px solid #65c8d0;
  outline-offset: 3px;
}
.scene-viewport svg {
  display: block;
  width: 100%;
  max-height: 65vh;
}
@media (max-width: 600px) {
  .scene-controls {
    gap: 0.5rem;
  }
  .scene-controls select {
    max-width: 12rem;
  }
}

.scene p,
.observation {
  overflow-wrap: anywhere;
}
.scene-controls label {
  max-width: 100%;
  flex-wrap: wrap;
}
/* Part VI keeps detailed formulas and numerical provenance next to the experiment. */
.calculation-details, .formula-index { margin: 1rem 0; padding: 1rem; border: 1px solid #35435a; border-radius: .6rem; }
.calculation-details pre { max-height: 28rem; overflow: auto; font-size: .78rem; white-space: pre-wrap; overflow-wrap: anywhere; }
.formula-index input { width: 100%; margin: .7rem 0; }
.formula-matches { max-height: 28rem; overflow: auto; }
.formula-matches button { display: block; width: 100%; text-align: left; margin: .4rem 0; }
.formula-matches span { display: block; font-size: .75rem; max-height: 4rem; overflow: hidden; white-space: pre-wrap; overflow-wrap: anywhere; }