*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --text-primary: #111;
  --text-secondary: #666;
  --bg: #fff;
  --border: #e5e5e5;
  --accent: #111;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  color: var(--text-primary);
  background: var(--bg);
  line-height: 1.6;
  min-height: 100vh;
}

/* ── Screens ─────────────────────────────────────────────────────────────── */

.screen { display: none; }

.screen.active {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
}

/* ── Upload screen ───────────────────────────────────────────────────────── */

.upload-container {
  width: min(480px, 92vw);
  padding: 4rem 1.5rem;
}

h1 {
  font-size: 3rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 0.5rem;
}

.subtitle {
  color: var(--text-secondary);
  font-size: 1rem;
  margin-bottom: 2.5rem;
  line-height: 1.6;
}

/* Drop zone */
.drop-zone {
  position: relative;
  border: 1px solid var(--border);
  min-height: 160px;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  cursor: pointer;
  transition: border-color 0.15s;
  margin-bottom: 1.5rem;
}

.drop-zone:hover,
.drop-zone.drag-over {
  border-color: var(--text-primary);
}

.drop-zone input[type="file"] {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
  width: 100%;
  height: 100%;
}

.drop-inner {
  text-align: center;
  pointer-events: none;
  padding: 1rem;
}

.drop-icon {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
  color: var(--text-secondary);
}

.drop-inner p {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.preview-img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  max-height: 220px;
  display: block;
}

.preview-img.hidden { display: none; }
.drop-inner.hidden  { display: none; }

/* Settings */
.settings {
  margin-bottom: 1.5rem;
}

.slider-label {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.slider-label strong {
  color: var(--text-primary);
  font-size: 1rem;
}

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

.examples {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem 0.75rem;
  margin-top: 1.25rem;
}

.examples-label {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.btn-example {
  background: none;
  border: none;
  border-bottom: 1px solid var(--text-secondary);
  padding: 0;
  font-family: inherit;
  font-size: 0.85rem;
  color: var(--text-secondary);
  cursor: pointer;
  transition: opacity 0.2s;
}

.btn-example:hover { opacity: 0.6; }

.upload-msg {
  font-size: 0.85rem;
  color: #c00;
  min-height: 1.2rem;
  margin-bottom: 0.75rem;
}

/* Buttons */
.btn-primary {
  width: 100%;
  padding: 0.75rem;
  background: var(--text-primary);
  color: var(--bg);
  border: 1px solid var(--text-primary);
  border-radius: 0;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  cursor: pointer;
  transition: opacity 0.2s;
}

.btn-primary:hover:not(:disabled) { opacity: 0.75; }
.btn-primary:active:not(:disabled) { opacity: 0.6; }
.btn-primary:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.btn-secondary {
  background: none;
  border: none;
  padding: 0;
  font-family: inherit;
  font-size: 0.9rem;
  color: var(--text-secondary);
  cursor: pointer;
  border-bottom: 1px solid var(--text-secondary);
  transition: opacity 0.2s;
  margin-top: 1.5rem;
  display: inline-block;
}

.btn-secondary:hover { opacity: 0.6; }

/* ── Game screen ─────────────────────────────────────────────────────────── */

#game-screen.active {
  align-items: flex-start;
  padding: 3rem 1.5rem;
}

.game-layout {
  display: flex;
  gap: 3rem;
  width: 100%;
  max-width: 960px;
  margin: 0 auto;
  align-items: flex-start;
}

/* Canvas */
.canvas-area {
  flex: 1;
  min-width: 0;
}

#puzzle-canvas {
  display: block;
  border: 1px solid var(--border);
  cursor: crosshair;
  max-width: 100%;
  image-rendering: pixelated;
  image-rendering: crisp-edges;
}

/* Sidebar */
.sidebar {
  width: 180px;
  flex-shrink: 0;
  padding-top: 0.25rem;
}

.sidebar h2 {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-secondary);
  margin-bottom: 1rem;
}

/* Palette */
.palette {
  display: flex;
  flex-direction: column;
}

.palette-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 0.4rem 0;
  border-bottom: 1px solid var(--border);
  user-select: none;
  cursor: pointer;
  transition: opacity 0.15s;
}

.palette-item:hover {
  opacity: 0.6;
}

.palette-item.selected {
  opacity: 1;
}

.palette-item.selected .pal-num {
  color: var(--text-primary);
  font-weight: 700;
}

/* Dim everything else when a color is selected */
.palette:has(.selected) .palette-item:not(.selected) {
  opacity: 0.3;
}

.palette-item.complete {
  opacity: 0.35;
}

.palette-item.complete .pal-num {
  text-decoration: line-through;
}

.pal-num {
  font-size: 0.8rem;
  font-weight: 600;
  width: 18px;
  text-align: right;
  color: var(--text-secondary);
  flex-shrink: 0;
  letter-spacing: -0.01em;
}

.pal-swatch {
  width: 24px;
  height: 16px;
  border: 1px solid rgba(0,0,0,0.1);
  flex-shrink: 0;
}

.pal-check {
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-weight: 600;
  margin-left: auto;
}

.pal-check.hidden { display: none; }

/* Progress */
.progress-wrap {
  margin-top: 1.5rem;
}

.progress-label {
  font-size: 0.8rem;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

.progress-bar-track {
  background: var(--border);
  height: 2px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: var(--text-primary);
  width: 0%;
  transition: width 0.3s ease;
}

/* Win overlay */
.win-overlay {
  position: fixed;
  inset: 0;
  background: rgba(255,255,255,0.92);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
}

.win-overlay.hidden { display: none; }

.win-box {
  text-align: center;
  padding: 3rem 2rem;
}

.win-icon {
  font-size: 2.5rem;
  margin-bottom: 0.75rem;
  line-height: 1;
}

.win-box h2 {
  font-size: 2rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  margin-bottom: 0.5rem;
}

.win-sub {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 1.25rem;
}

.reference-canvas {
  display: block;
  margin: 0 auto 1.5rem;
  border: 1px solid var(--border);
  max-width: 100%;
  image-rendering: pixelated;
  image-rendering: crisp-edges;
}

.win-box .btn-primary {
  width: auto;
  padding: 0.65rem 2rem;
}

/* Mobile */
@media (max-width: 768px) {
  h1 { font-size: 2rem; }

  /* Remove side padding so canvas goes edge-to-edge */
  #game-screen.active {
    padding: 1.5rem 0 2rem;
    align-items: flex-start;
  }

  .game-layout {
    flex-direction: column;
    gap: 1.5rem;
  }

  .canvas-area {
    width: 100%;
  }

  /* Sidebar gets its own horizontal padding below the canvas */
  .sidebar {
    width: 100%;
    padding: 0 1rem;
  }

  .palette {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    gap: 0;
  }
}