:root {
  --bg: #f7f5f0;
  --panel: #ffffff;
  --text: #1f2328;
  --muted: #5d636b;
  --border: #dedad2;
  --accent: #b4442c;
  --accent-text: #ffffff;
  --error: #b42318;
  --focus: #2d6cdf;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111316;
    --panel: #1a1d21;
    --text: #e8e6e1;
    --muted: #a1a7ae;
    --border: #2e3238;
    --accent: #e0775c;
    --accent-text: #111316;
    --error: #ff8a7a;
    --focus: #7fa8ff;
    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;
}

header,
main,
footer {
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 16px;
}

header {
  padding-top: 20px;
}

h1 {
  margin: 0;
  font-size: 1.7rem;
  letter-spacing: 0.02em;
}

.subtitle {
  margin: 4px 0 16px;
  color: var(--muted);
  max-width: 70ch;
}

main {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: 20px;
  align-items: start;
}

.stage {
  min-width: 0;
}

#board {
  display: block;
  width: 100%;
  aspect-ratio: 1 / 1;
  max-height: 80vh;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--bg);
  cursor: crosshair;
  touch-action: none;
}

#board.panning {
  cursor: grabbing;
}

.status {
  min-height: 1.5em;
  margin: 8px 0 0;
  font-weight: 600;
}

.hint,
.help,
.keys {
  color: var(--muted);
  font-size: 0.85rem;
  margin: 4px 0;
}

.panel {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

fieldset {
  margin: 0;
  padding: 10px 12px 12px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: var(--panel);
}

legend {
  padding: 0 4px;
  font-weight: 600;
}

label {
  display: block;
  margin: 8px 0 2px;
  font-size: 0.9rem;
}

label.inline {
  display: inline;
  margin: 0;
}

label.check[hidden] {
  display: none;
}

label.check {
  display: flex;
  gap: 6px;
  align-items: center;
}

select,
input[type='text'],
input[type='number'] {
  width: 100%;
  padding: 5px 8px;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: var(--bg);
  color: var(--text);
  font: inherit;
}

#rule {
  font-family: ui-monospace, 'Cascadia Mono', Consolas, monospace;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

#rule[aria-invalid='true'] {
  border-color: var(--error);
}

input[type='range'] {
  width: 100%;
  accent-color: var(--accent);
}

.row {
  display: flex;
  gap: 6px;
  align-items: center;
  margin-top: 8px;
}

.row.buttons {
  flex-wrap: wrap;
}

#jump-form input {
  flex: 1;
  min-width: 0;
}

button {
  padding: 5px 10px;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: var(--bg);
  color: var(--text);
  font: inherit;
  cursor: pointer;
}

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

button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-text);
  min-width: 5em;
}

:focus-visible {
  outline: 2px solid var(--focus);
  outline-offset: 2px;
}

.note {
  margin: 6px 0 4px;
  font-size: 0.9rem;
}

.error {
  min-height: 0;
  margin: 2px 0;
  color: var(--error);
  font-size: 0.85rem;
}

.error:empty {
  display: none;
}

.swatches {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin: 8px 0 0;
  padding: 0;
  list-style: none;
}

.swatches li {
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border: 1px solid var(--border);
  border-radius: 4px;
  font: 600 0.8rem ui-monospace, Consolas, monospace;
}

table.machine {
  width: 100%;
  margin-top: 8px;
  border-collapse: collapse;
  font: 0.8rem ui-monospace, Consolas, monospace;
}

table.machine caption {
  text-align: left;
  color: var(--muted);
  font-family: system-ui, sans-serif;
  padding-bottom: 2px;
}

table.machine th,
table.machine td {
  padding: 2px 4px;
  border: 1px solid var(--border);
  text-align: center;
}

table.machine th {
  font-weight: 600;
}

.readout {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 2px 12px;
  margin: 0;
}

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

.readout dd {
  margin: 0;
  text-align: right;
  font-variant-numeric: tabular-nums;
}

.pattern {
  margin: 8px 0 0;
  font-size: 0.9rem;
}

kbd {
  padding: 0 4px;
  border: 1px solid var(--border);
  border-radius: 3px;
  font-size: 0.8rem;
}

footer {
  margin: 24px auto;
  color: var(--muted);
  font-size: 0.85rem;
}

footer a {
  color: inherit;
}

@media (max-width: 860px) {
  main {
    grid-template-columns: minmax(0, 1fr);
  }
}