:root {
  --bg: #f6f7f9;
  --panel: #ffffff;
  --text: #1c2026;
  --muted: #5d6673;
  --border: #dde1e6;
  --accent: #3b4cc0;
  --gold: #c99a0e;
  --good: #1f7a3d;
  --bad: #b40426;
  --grid: rgba(0, 0, 0, 0.12);
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14171b;
    --panel: #1c2026;
    --text: #e7ebef;
    --muted: #9aa3ae;
    --border: #2f353d;
    --accent: #8d9cf5;
    --gold: #e8bd36;
    --good: #5fc27e;
    --bad: #f06b7f;
    --grid: rgba(0, 0, 0, 0.35);
    color-scheme: dark;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 15px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

h1,
h2 {
  margin: 0 0 0.5rem;
  line-height: 1.2;
}

h1 {
  font-size: 1.6rem;
}

h2 {
  font-size: 1.05rem;
}

a {
  color: var(--accent);
}

code {
  font: 0.95em/1.4 ui-monospace, "Cascadia Mono", Consolas, monospace;
  overflow-wrap: anywhere;
}

header.site,
footer.site,
.layout {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 16px;
}

header.site {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 2rem;
  align-items: flex-end;
  justify-content: space-between;
  padding-top: 24px;
  padding-bottom: 16px;
}

header.site p {
  margin: 0;
  max-width: 62ch;
  color: var(--muted);
}

header.site .model-info {
  font-size: 0.85rem;
  text-align: right;
}

.layout {
  display: grid;
  gap: 16px;
  grid-template-columns: minmax(280px, 360px) minmax(0, 1fr);
  grid-template-areas:
    "controls result"
    "spacetime steps"
    "accuracy accuracy"
    "tasks tasks";
}

.controls {
  grid-area: controls;
}

.result {
  grid-area: result;
}

.spacetime {
  grid-area: spacetime;
}

.stepview {
  grid-area: steps;
}

.accuracy {
  grid-area: accuracy;
}

.tasks {
  grid-area: tasks;
}

.panel[hidden] {
  display: none;
}

@media (max-width: 860px) {
  .layout {
    grid-template-columns: minmax(0, 1fr);
    grid-template-areas: "controls" "result" "steps" "spacetime" "accuracy" "tasks";
  }
}

.panel {
  min-width: 0;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px;
}

.field {
  display: flex;
  flex: 1;
  flex-direction: column;
  gap: 4px;
  margin-bottom: 12px;
  min-width: 0;
}

.field span {
  font-size: 0.85rem;
  color: var(--muted);
}

input,
select,
button {
  font: inherit;
  color: inherit;
}

input[type="text"],
input[type="number"],
select {
  width: 100%;
  padding: 6px 8px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
}

#input {
  font-family: ui-monospace, "Cascadia Mono", Consolas, monospace;
}

input:disabled {
  color: var(--muted);
}

input[aria-invalid="true"] {
  border-color: var(--bad);
}

button {
  padding: 5px 10px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
}

button:hover {
  border-color: var(--accent);
}

.buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin: -4px 0 16px;
}

.buttons button {
  font-size: 0.85rem;
  padding: 3px 8px;
}

.row {
  display: flex;
  gap: 12px;
  align-items: flex-end;
}

.row > button,
.row > .check {
  margin-bottom: 12px;
}

.check {
  display: flex;
  gap: 6px;
  align-items: center;
  margin-bottom: 12px;
  font-size: 0.9rem;
  white-space: nowrap;
}

.error {
  min-height: 1.5em;
  margin: 0;
  color: var(--bad);
  font-size: 0.9rem;
}

.badge {
  margin-left: 6px;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 500;
  vertical-align: middle;
  border: 1px solid currentColor;
}

.badge.in {
  color: var(--good);
}

.badge.out {
  color: var(--gold);
}

dl {
  display: grid;
  grid-template-columns: max-content minmax(0, 1fr);
  gap: 8px 16px;
  margin: 12px 0;
}

dt {
  color: var(--muted);
}

dd {
  margin: 0;
  min-width: 0;
}

.result code {
  font-size: 1.1rem;
}

.verdict.good {
  color: var(--good);
  font-weight: 600;
}

.verdict.bad {
  color: var(--bad);
  font-weight: 600;
}

.note,
.hint,
.readout {
  color: var(--muted);
  font-size: 0.85rem;
}

.hint {
  margin-top: 0;
}

.panel-heading {
  display: flex;
  gap: 10px;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.5rem;
}

.panel-heading h2 {
  margin: 0;
}

.panel-heading select {
  width: auto;
}

.readout {
  min-height: 1.5em;
  margin: 6px 0;
  font-variant-numeric: tabular-nums;
}

.canvas-wrap {
  width: 100%;
}

canvas {
  display: block;
  touch-action: none;
}

#spacetime {
  cursor: crosshair;
}

.legend {
  display: flex;
  gap: 8px;
  align-items: center;
  color: var(--muted);
  font-size: 0.8rem;
}

.legend i {
  flex: 0 1 180px;
  height: 8px;
  border-radius: 2px;
  background: linear-gradient(90deg, rgb(59, 76, 192), rgb(245, 245, 245), rgb(180, 4, 38));
}

.timeline {
  display: flex;
  gap: 10px;
  align-items: center;
  margin-bottom: 10px;
}

.timeline input {
  flex: 1;
  min-width: 0;
}

#play {
  width: 2.4rem;
}

footer.site {
  padding-top: 24px;
  padding-bottom: 32px;
  color: var(--muted);
}

footer.site p {
  max-width: 80ch;
}

/* Loading and computing indicators */
.busy {
  display: inline-flex;
  gap: 6px;
  align-items: center;
  margin-left: 8px;
  color: var(--muted);
  font-size: 0.8rem;
  font-weight: 400;
  vertical-align: middle;
}

.busy[hidden] {
  display: none;
}

.spinner {
  display: inline-block;
  width: 12px;
  height: 12px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  vertical-align: -1px;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

@media (prefers-reduced-motion: reduce) {
  .spinner {
    animation-duration: 2.4s;
  }
}

body.loading .controls,
body.loading .spacetime,
body.loading .stepview,
.stale {
  opacity: 0.45;
  pointer-events: none;
  transition: opacity 0.15s;
}

/* Measured accuracy table */
.table-wrap {
  overflow-x: auto;
}

table {
  border-collapse: collapse;
  font-variant-numeric: tabular-nums;
}

th,
td {
  padding: 5px 10px;
  border-bottom: 1px solid var(--border);
  text-align: right;
  white-space: nowrap;
}

th:first-child,
td:first-child {
  padding-left: 0;
  text-align: left;
}

thead th {
  color: var(--muted);
  font-weight: 500;
  cursor: help;
}

tr.current td {
  font-weight: 600;
}

tr.current td:first-child::before {
  content: "▸ ";
  color: var(--accent);
}

tfoot td {
  border-bottom: none;
  color: var(--muted);
}

ul.note {
  margin: 10px 0 0;
  padding-left: 1.1rem;
}

/* Task definitions */
.task-hint {
  margin: -6px 0 12px;
}

.task-list {
  grid-template-columns: max-content max-content minmax(0, 1fr);
  gap: 8px 24px;
  align-items: baseline;
}

.task-list dt {
  color: var(--text);
  font-weight: 500;
}

.task-list .formula {
  margin: 0;
  font-family: "Cambria Math", "STIX Two Math", Georgia, serif;
  white-space: nowrap;
}

.task-list .example {
  margin: 0;
  color: var(--muted);
}

.task-list .current {
  color: var(--accent);
}

@media (max-width: 640px) {
  .task-list {
    grid-template-columns: minmax(0, 1fr);
    gap: 2px;
  }

  .task-list dt {
    margin-top: 10px;
  }
}

th.group {
  text-align: center;
  border-bottom: none;
  padding-bottom: 0;
}

thead th[data-mode] {
  font-size: 0.8rem;
}

td.active-mode,
th.active-mode {
  background: color-mix(in srgb, var(--accent) 10%, transparent);
}

thead tr + tr th:first-child {
  padding-left: 10px;
  text-align: right;
}

footer.site h3 {
  margin: 1.2rem 0 0.3rem;
  color: var(--text);
  font-size: 0.95rem;
}

table caption {
  caption-side: top;
  padding-bottom: 6px;
  color: var(--muted);
  font-size: 0.85rem;
  text-align: left;
}

/* Long checkpoint paths have no natural break points. */
#provenance {
  overflow-wrap: anywhere;
}

@media (max-width: 640px) {
  table {
    font-size: 0.8rem;
  }

  th,
  td {
    padding: 4px 5px;
  }

  td:first-child {
    white-space: normal;
  }
}