:root {
  --bg: #0f1114;
  --grid-cell: #1d2126;
  --grid-stroke: #2a2f36;
  --text: #e8eaed;
  --text-muted: rgba(232, 234, 237, 0.72);
  --heat-base: rgba(58, 199, 183, 0.35);
  --path-teal: #2dd4bf;
  --start: #7dd3fc;
  --goal: #fca5a5;
  --wall: #13171e;
  --radius: 8px;
  --transition: 160ms ease;
  --max-width: min(96vw, 1080px);
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

body {
  display: flex;
  justify-content: center;
  padding: clamp(16px, 4vw, 48px) 12px 60px;
}

.skip-link {
  position: absolute;
  top: -40px;
  left: 12px;
  padding: 8px 12px;
  background: var(--path-gold);
  color: var(--bg);
  text-decoration: none;
  border-radius: 4px;
  transition: top var(--transition);
  z-index: 10;
}

.skip-link:focus {
  top: 12px;
}

.app {
  width: var(--max-width);
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: clamp(16px, 3vw, 40px);
  border: 1px solid var(--grid-stroke);
  border-radius: var(--radius);
  padding: clamp(16px, 3vw, 32px);
  background: linear-gradient(160deg, rgba(20, 22, 27, 0.9), rgba(15, 17, 20, 0.94));
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4);
}

.controls-header {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin-bottom: 16px;
}

.controls h1 {
  font-size: clamp(1.5rem, 3vw, 2.1rem);
  margin: 0;
}

.controls .tagline {
  margin: 0;
  color: var(--text-muted);
  letter-spacing: 0.02em;
}

.path-summary {
  margin: 0;
  font-size: 0.95rem;
  color: rgba(214, 180, 106, 0.92);
}

.control-panel {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.control-group {
  border: 1px solid rgba(67, 73, 84, 0.6);
  border-radius: 8px;
  padding: 12px 14px;
  display: grid;
  gap: 12px;
  background: rgba(21, 24, 30, 0.55);
}

.control-group legend {
  padding: 0 6px;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-muted);
}

.field {
  display: flex;
  flex-direction: column;
  gap: 4px;
  font-size: 0.9rem;
}

.field span {
  color: var(--text-muted);
}

.field select {
  background: rgba(29, 33, 38, 0.9);
  border: 1px solid rgba(67, 73, 84, 0.8);
  border-radius: 6px;
  padding: 8px 10px;
  color: var(--text);
  font-size: 0.95rem;
  transition: border var(--transition), background var(--transition);
}

.field select:focus-visible {
  outline: 2px solid var(--path-gold);
  outline-offset: 2px;
}

.field.checkbox,
.field.radio {
  flex-direction: row;
  align-items: center;
  gap: 10px;
}

.field.checkbox input,
.field.radio input {
  width: 18px;
  height: 18px;
  accent-color: var(--path-gold);
}

.field.checkbox span,
.field.radio span {
  color: var(--text);
}

.field.is-disabled span,
.field.is-disabled select {
  opacity: 0.5;
  pointer-events: none;
}

.control-actions {
  display: flex;
  gap: 12px;
}

.control-actions button {
  flex: 1;
  border: 1px solid rgba(214, 180, 106, 0.6);
  background: rgba(214, 180, 106, 0.12);
  color: var(--text);
  border-radius: 6px;
  padding: 10px 12px;
  font-size: 0.95rem;
  cursor: pointer;
  transition: background var(--transition), border var(--transition), transform var(--transition);
}

.control-actions button[aria-pressed='false'] {
  border-color: rgba(214, 180, 106, 0.85);
  background: rgba(234, 179, 8, 0.18);
}

.control-actions button[aria-pressed='true'] {
  border-color: rgba(45, 212, 191, 0.85);
  background: rgba(45, 212, 191, 0.28);
  box-shadow: 0 0 14px rgba(45, 212, 191, 0.28);
}

.control-actions button:hover {
  background: rgba(214, 180, 106, 0.25);
  border-color: rgba(214, 180, 106, 0.9);
}

.control-actions button:active {
  transform: translateY(1px);
}

.grid-wrapper {
  display: flex;
  align-items: center;
  justify-content: center;
}

.grid-stage {
  position: relative;
  width: min(100%, 840px);
  aspect-ratio: 3 / 2;
  border-radius: calc(var(--radius) - 2px);
  border: 1px solid var(--grid-stroke);
  background: var(--grid-cell);
  overflow: hidden;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.02);
}

.grid {
  position: absolute;
  inset: 0;
  display: grid;
  gap: 1px;
  background: var(--grid-stroke);
  padding: 1px;
  touch-action: none;
  user-select: none;
  cursor: default;
}

.grid-cell {
  position: relative;
  background: var(--grid-cell);
  width: 100%;
  aspect-ratio: 1 / 1;
  border-radius: 2px;
  transition: background var(--transition), transform var(--transition), box-shadow var(--transition);
  touch-action: none;
  user-select: none;
  cursor: pointer;
}

.grid-cell::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 2px;
  background: radial-gradient(ellipse at center, rgba(45, 212, 191, 0.35) 0%, rgba(37, 99, 235, 0) 75%);
  opacity: var(--heat-opacity, 0);
  transition: opacity var(--transition);
  pointer-events: none;
}

.grid-cell::after {
  content: '';
  position: absolute;
  inset: 50% auto auto 50%;
  width: 76%;
  height: 76%;
  transform: translate(-50%, -50%);
  transition: transform var(--transition), background var(--transition), opacity var(--transition);
  pointer-events: none;
  opacity: 0;
}

.grid-cell[data-state='start']::after {
  opacity: 1;
  border-radius: 999px;
  background: radial-gradient(circle at 30% 30%, #f5f3ff 0%, #c084fc 65%, #7c3aed 100%);
  box-shadow: 0 0 12px rgba(192, 132, 252, 0.6);
  outline: 2px solid #1f2937;
  outline-offset: -1px;
}

.grid-cell[data-state='goal']::after {
  opacity: 1;
  background: radial-gradient(circle at 50% 15%, #fef9c3 0%, #facc15 50%, #ca8a04 100%);
  clip-path: polygon(50% 6%, 92% 94%, 8% 94%);
  box-shadow: 0 0 12px rgba(250, 204, 21, 0.5);
  outline: 2px solid #1f2937;
  outline-offset: -1px;
}

.grid-cell[data-state='wall'] {
  background: rgba(239, 68, 68, 0.9);
  box-shadow: inset 0 0 0 2px rgba(185, 28, 28, 0.75);
}

.grid-cell[data-state='wall']::before {
  opacity: 0;
}

.grid-cell[data-path='true']::before {
  background: rgba(45, 212, 191, 0.35);
  opacity: 1;
  box-shadow: inset 0 0 0 1px rgba(13, 148, 136, 0.6);
}

.grid-cell[data-path='true'][data-state='start']::after,
.grid-cell[data-path='true'][data-state='goal']::after {
  box-shadow: 0 0 16px rgba(37, 99, 235, 0.5);
}

.grid-cell[data-token] {
  cursor: grab;
}

.grid-cell[data-dragging='true'] {
  cursor: grabbing;
}

.grid-cell:focus-visible {
  outline: 2px solid var(--path-gold);
  outline-offset: 1px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 960px) {
  .app {
    grid-template-columns: 1fr;
  }

  .grid-stage {
    width: 100%;
    aspect-ratio: 4 / 3;
  }
}

@media (max-width: 600px) {
  body {
    padding: 12px 8px 48px;
  }

  .app {
    display: flex;
    flex-direction: column;
    gap: 20px;
  }

  .grid-wrapper {
    order: -1;
  }

  .controls {
    order: 0;
  }

  .grid-stage {
    aspect-ratio: 1;
  }

  .control-actions {
    flex-direction: column;
  }
}