:root {
  /* Surfaces and text */
  --color-bg: #fff4dc;
  --color-surface: #fffbf0;
  --color-ink: #2a1c10;
  --color-ink-muted: #5e4a36;
  --color-line: #8b7355;
  --color-rail: #8b7355;
  --color-neutral-fill: #e5d9c3;

  /* Roles */
  --color-focus: #1b4dff;
  --color-on-fill: #ffffff;
  --color-over: #b3261e;
  --color-live: #0b6e6e;
  --color-tunnel-a: #0b6e6e;
  --color-tunnel-b: #8a4b00;
  --color-tunnel-c: #6b2f8f;
  --color-practice: #16203a;
  --color-practice-soft: #e4e9f7;
  --color-practice-stripe: #ffd34d;

  /* Border style of data surfaces. Practice swaps this to dashed. */
  --surface-border-style: solid;

  /* Type scale */
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.25rem;
  --text-xl: 1.75rem;
  --text-2xl: 2.25rem;
  --font-body: ui-rounded, "SF Pro Rounded", "Hiragino Maru Gothic ProN", "Nunito", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-data: ui-monospace, "SF Mono", Menlo, Consolas, monospace;

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-6: 1.5rem;
  --space-8: 2rem;

  --radius-sm: 0.5rem;
  --radius-md: 0.75rem;
  --radius-arch: 2.5rem;
}

/* The practice board re-tints every surface, so it can never pass for real Sepolia data. */
body[data-board="practice"] {
  --color-bg: #e4e9f7;
  --color-surface: #f4f6fd;
  --color-ink: #16203a;
  --color-ink-muted: #3f4a66;
  --color-line: #5d6a8c;
  --color-rail: #5d6a8c;
  --color-neutral-fill: #cdd5ea;
  --surface-border-style: dashed;
}

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

[hidden] {
  display: none !important;
}

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-ink);
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.5;
}

h1,
h2,
h3,
p,
ol,
ul,
dl,
dd {
  margin: 0;
  padding: 0;
}

ol,
ul {
  list-style: none;
}

h1,
h2,
h3 {
  line-height: 1.15;
  text-wrap: balance;
}

h1 {
  font-size: var(--text-xl);
  font-weight: 800;
  letter-spacing: -0.02em;
}

h2 {
  font-size: var(--text-lg);
  font-weight: 800;
}

h3 {
  font-size: var(--text-base);
  font-weight: 800;
}

:focus-visible {
  outline: 3px solid var(--color-focus);
  outline-offset: 2px;
}

.sprites {
  position: absolute;
  inline-size: 0;
  block-size: 0;
}

.visually-hidden {
  position: absolute;
  inline-size: 1px;
  block-size: 1px;
  margin: -1px;
  padding: 0;
  border: 0;
  overflow: hidden;
  clip-path: inset(50%);
  white-space: nowrap;
}

.value {
  font-variant-numeric: tabular-nums;
  overflow-wrap: anywhere;
}

.link {
  color: inherit;
  font-weight: 700;
  text-decoration-line: underline;
  text-underline-offset: 0.15em;
  overflow-wrap: anywhere;
}

.note {
  color: var(--color-ink-muted);
  font-size: var(--text-sm);
  text-wrap: pretty;
}

/* Page frame */
.page {
  max-inline-size: 72rem;
  margin-inline: auto;
  padding-block: var(--space-3) var(--space-8);
  padding-inline: max(var(--space-3), env(safe-area-inset-left)) max(var(--space-3), env(safe-area-inset-right));
}

.masthead {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  column-gap: var(--space-4);
}

.masthead-link {
  display: inline-flex;
  align-items: center;
  min-block-size: 2.75rem;
  color: inherit;
  font-weight: 700;
  text-decoration-line: underline;
  text-underline-offset: 0.15em;
}

.lede {
  margin-block-end: var(--space-3);
  color: var(--color-ink-muted);
  text-wrap: pretty;
}

.layout {
  display: grid;
  gap: var(--space-8);
}

main {
  min-inline-size: 0;
}

/* Buttons */
.btn,
.send {
  min-block-size: 2.75rem;
  border-radius: var(--radius-md);
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  touch-action: manipulation;
}

.btn {
  padding: var(--space-2) var(--space-3);
  border: 2px solid var(--color-ink);
  background: var(--color-surface);
  color: var(--color-ink);
}

.btn-primary {
  border-color: var(--color-ink);
  background: var(--color-ink);
  color: var(--color-bg);
}

.btn-practice {
  border-style: dashed;
  border-color: var(--color-practice);
  background: var(--color-practice-soft);
  color: var(--color-practice);
}

.btn:disabled,
.send:disabled {
  border-color: transparent;
  background: var(--color-neutral-fill);
  color: var(--color-ink-muted);
  cursor: not-allowed;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

.controls {
  margin-block-start: var(--space-4);
}

.controls .btn {
  flex: 1 1 0;
  min-inline-size: 5.5rem;
}

/* Notice states */
.notice-panel {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  padding: var(--space-4);
  border-radius: var(--radius-md);
  background: var(--color-surface);
}

.notice-panel > div {
  display: grid;
  flex: 1 1 14rem;
  gap: var(--space-3);
}

.hamster {
  flex: none;
  inline-size: 3.5rem;
  block-size: 3.5rem;
}

/* Status */
.practice-banner {
  margin-block-end: var(--space-3);
  padding: calc(var(--space-3) + 0.5rem) var(--space-3) var(--space-3);
  border-radius: var(--radius-sm);
  background:
    repeating-linear-gradient(135deg, var(--color-practice-stripe) 0 12px, var(--color-practice) 12px 24px) top / 100% 0.5rem no-repeat,
    var(--color-practice);
  color: var(--color-on-fill);
  font-weight: 700;
}

.status-row {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-1) var(--space-3);
  margin-block-end: var(--space-3);
  font-size: var(--text-sm);
}

.source-label {
  font-weight: 800;
}

.source-label::before {
  content: "";
  display: inline-block;
  inline-size: 0.625rem;
  block-size: 0.625rem;
  margin-inline-end: var(--space-1);
  border-radius: 50%;
  background: var(--color-live);
}

body[data-board="practice"] .source-label::before {
  border-radius: 0;
  background: var(--color-practice);
}

.status-item .value {
  font-weight: 800;
}

.refresh-status {
  margin-block-end: var(--space-3);
}

.status-goal {
  color: var(--color-ink-muted);
}

/* Train */
.train {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: var(--space-2);
  padding-block-end: var(--space-3);
  border-block-end: 3px solid var(--color-rail);
  margin-block-end: var(--space-4);
}

.wagon {
  position: relative;
  display: grid;
  justify-items: center;
  align-content: start;
  padding: var(--space-1) var(--space-1) var(--space-2);
  border: 2px var(--surface-border-style) var(--color-line);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  font-size: var(--text-sm);
  text-align: center;
  overflow-wrap: anywhere;
}

.wagon::before,
.wagon::after {
  content: "";
  position: absolute;
  inset-block-end: calc(-1 * var(--space-3));
  inline-size: 0.625rem;
  block-size: 0.625rem;
  border-radius: 50%;
  background: var(--color-ink);
  pointer-events: none;
}

.wagon::before {
  inset-inline-start: 18%;
}

.wagon::after {
  inset-inline-end: 18%;
}

.wagon-number {
  color: var(--color-ink-muted);
}

.wagon-blocks {
  font-size: var(--text-lg);
  font-weight: 800;
  line-height: 1.2;
}

.wagon[data-state="now"] {
  border-color: var(--color-ink);
  border-style: solid;
  background: var(--color-ink);
  color: var(--color-bg);
}

.wagon[data-state="now"] .wagon-number {
  color: inherit;
}

.wagon[data-state="sent"] {
  border-color: transparent;
  color: var(--color-on-fill);
}

.wagon[data-state="sent"] .wagon-number {
  color: inherit;
}

.wagon[data-tunnel="0"] {
  background: var(--color-tunnel-a);
}

.wagon[data-tunnel="1"] {
  background: var(--color-tunnel-b);
}

.wagon[data-tunnel="2"] {
  background: var(--color-tunnel-c);
}

.wagon-state {
  font-weight: 700;
}

/* Current wagon */
.current {
  display: flex;
  gap: var(--space-3);
  align-items: flex-start;
}

.current-body {
  display: grid;
  flex: 1 1 0;
  min-inline-size: 0;
  gap: var(--space-1);
}

.facts {
  display: grid;
  gap: var(--space-1);
  font-size: var(--text-sm);
}

.facts > div {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  column-gap: var(--space-3);
}

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

.facts dd {
  font-weight: 700;
  min-inline-size: 0;
}

.current .link {
  display: inline-flex;
  align-items: center;
  justify-self: start;
  min-block-size: 2.75rem;
}

/* Switch rails */
.rails {
  display: block;
  inline-size: 100%;
  block-size: 2.5rem;
  margin-block-start: var(--space-2);
}

.rail {
  fill: none;
  stroke: var(--color-rail);
  stroke-width: 4;
  stroke-dasharray: 3 5;
}

.rails[data-last] .rail {
  opacity: 0.45;
}

.rails[data-last="0"] .rail-0 {
  opacity: 1;
  stroke: var(--color-tunnel-a);
  stroke-dasharray: none;
}

.rails[data-last="1"] .rail-1 {
  opacity: 1;
  stroke: var(--color-tunnel-b);
  stroke-dasharray: none;
}

.rails[data-last="2"] .rail-2 {
  opacity: 1;
  stroke: var(--color-tunnel-c);
  stroke-dasharray: none;
}

/* Tunnels */
.tunnels {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: var(--space-2);
  margin-block-end: var(--space-2);
}

.tunnel {
  --tunnel: var(--color-tunnel-a);
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  min-inline-size: 0;
  padding: var(--space-4) var(--space-2) var(--space-2);
  border: 3px var(--surface-border-style) var(--tunnel);
  border-radius: var(--radius-arch) var(--radius-arch) var(--radius-md) var(--radius-md);
  background: var(--color-surface);
  text-align: center;
  overflow-wrap: anywhere;
}

.tunnel[data-tunnel="1"] {
  --tunnel: var(--color-tunnel-b);
}

.tunnel[data-tunnel="2"] {
  --tunnel: var(--color-tunnel-c);
}

.tunnel-state {
  font-size: var(--text-sm);
  font-weight: 700;
}

.tunnel[data-state="over"] {
  border-color: var(--color-over);
  border-style: solid;
}

.tunnel[data-state="over"] .tunnel-state {
  color: var(--color-over);
}

.meter {
  display: block;
  block-size: 0.5rem;
  border-radius: var(--radius-sm);
  background: var(--color-neutral-fill);
}

.meter-fill {
  display: block;
  block-size: 100%;
  border-radius: inherit;
  background: var(--tunnel);
}

.tunnel[data-state="over"] .meter-fill {
  background: repeating-linear-gradient(135deg, var(--color-over) 0 4px, var(--color-ink) 4px 8px);
}

.tunnel-facts {
  display: grid;
  gap: 0;
  font-size: var(--text-sm);
  text-align: start;
}

.tunnel-facts > div {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  column-gap: var(--space-1);
}

.tunnel-facts dt {
  color: var(--color-ink-muted);
}

.tunnel-facts dd {
  font-weight: 700;
}

.tunnel[data-state="over"] .tunnel-facts > div:last-child dd {
  color: var(--color-over);
}

.send {
  margin-block-start: auto;
  padding: var(--space-1);
  border: 2px solid transparent;
  background: var(--tunnel);
  color: var(--color-on-fill);
}

/* Result */
.result {
  display: grid;
  gap: var(--space-3);
  margin-block-start: var(--space-4);
  padding: var(--space-4);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  overflow-wrap: anywhere;
}

.result h2 {
  font-size: var(--text-lg);
  scroll-margin-block-start: var(--space-4);
}

.result-verdict {
  font-weight: 700;
}

.routing {
  inline-size: 100%;
  border-collapse: collapse;
  font-size: var(--text-sm);
  text-align: start;
}

.routing caption {
  margin-block-end: var(--space-1);
  font-weight: 700;
  text-align: start;
}

.routing th,
.routing td {
  padding: var(--space-1) var(--space-2) var(--space-1) 0;
  border-block-end: 1px solid var(--color-line);
  text-align: start;
}

/* Manifest */
.manifest {
  margin-block-start: var(--space-8);
}

.manifest-list {
  display: grid;
  gap: var(--space-4);
  margin-block-start: var(--space-3);
}

.manifest-row {
  display: grid;
  gap: var(--space-1);
  padding-block-start: var(--space-3);
  border-block-start: 2px var(--surface-border-style) var(--color-line);
}

.hash {
  font-family: var(--font-data);
  font-weight: 400;
}

/* How to play */
.how {
  display: grid;
  align-content: start;
  gap: var(--space-3);
  scroll-margin-block-start: var(--space-4);
}

.how ol {
  display: grid;
  gap: var(--space-2);
  padding-inline-start: var(--space-6);
  list-style: decimal;
}

.shortcut-toggle {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  min-block-size: 2.75rem;
  font-weight: 700;
  cursor: pointer;
}

.shortcut-toggle input {
  inline-size: 1.25rem;
  block-size: 1.25rem;
  margin: 0;
}

/* Footer */
.footer {
  display: grid;
  gap: var(--space-2);
  margin-block-start: var(--space-8);
  padding-block-start: var(--space-4);
  border-block-start: 2px solid var(--color-line);
  font-size: var(--text-sm);
}

.footer ul {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1) var(--space-6);
}

.footer .link {
  display: inline-flex;
  align-items: center;
  min-block-size: 2.75rem;
}

@media (hover: hover) {
  .btn:hover:not(:disabled) {
    background: var(--color-neutral-fill);
  }

  .btn-primary:hover:not(:disabled) {
    background: var(--color-ink-muted);
  }

  .send:hover:not(:disabled) {
    border-color: var(--color-ink);
  }
}

@media (prefers-reduced-motion: no-preference) {
  .btn,
  .send {
    transition-property: transform, background-color, border-color;
    transition-duration: 150ms;
    transition-timing-function: ease-out;
  }

  .btn:active:not(:disabled),
  .send:active:not(:disabled) {
    transform: scale(0.96);
  }

  .meter-fill {
    transition: inline-size 150ms ease-out;
  }

  .wagon {
    transition-property: background-color, border-color, color;
    transition-duration: 150ms;
    transition-timing-function: ease-out;
  }
}

/* The side column appears once the yard still has room for three full tunnels beside it. */
@media (min-width: 62rem) {
  h1 {
    font-size: var(--text-2xl);
  }

  .page {
    padding-block-start: var(--space-6);
  }

  .lede {
    margin-block-end: var(--space-6);
  }

  .layout {
    grid-template-columns: minmax(0, 1fr) 20rem;
    align-items: start;
  }

  .tunnels {
    gap: var(--space-4);
  }

  .tunnel {
    padding-inline: var(--space-4);
    padding-block-end: var(--space-4);
  }

  .manifest-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}