/* ==========================================================================
   BOARD & WORD BUILDER STYLES
   ========================================================================== */

/* Active Word Construction Tray */
.word-builder-wrapper {
  margin: 6px 0 10px;
  position: relative;
  z-index: 10;
}

.word-builder {
  min-height: 52px;
  background: var(--bg-surface);
  backdrop-filter: blur(18px);
  -webkit-backdrop-filter: blur(18px);
  border: 1.5px solid var(--border-color);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 4px 8px;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.04);
  transition: all var(--transition-normal);
}

.word-builder.has-tiles {
  border-color: var(--border-highlight);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.08);
}

.word-builder.invalid-shake {
  animation: shake 0.45s cubic-bezier(0.36, 0.07, 0.19, 0.97) both;
  border-color: var(--accent-danger);
}

@keyframes shake {
  10%, 90% { transform: translate3d(-2px, 0, 0); }
  20%, 80% { transform: translate3d(4px, 0, 0); }
  30%, 50%, 70% { transform: translate3d(-6px, 0, 0); }
  40%, 60% { transform: translate3d(6px, 0, 0); }
}

/* Selected Tiles in Tray */
.active-tiles-container {
  display: flex;
  align-items: center;
  gap: 6px;
  flex: 1;
  min-height: 48px;
  overflow-x: auto;
  scrollbar-width: none;
  padding: 2px 4px;
}

.active-tiles-container::-webkit-scrollbar {
  display: none;
}

.builder-placeholder {
  color: var(--text-tertiary);
  font-size: 0.92rem;
  font-weight: 500;
  letter-spacing: -0.01em;
  padding-left: 8px;
}

/* Active Tile Chip */
.active-tile-chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 8px 14px;
  background: var(--tile-bg);
  color: var(--text-primary);
  border: 1.5px solid var(--tile-border);
  border-radius: var(--radius-md);
  font-size: 1.12rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  box-shadow: var(--tile-shadow);
  cursor: grab;
  position: relative;
  transition: transform var(--transition-fast), background var(--transition-fast), border-color var(--transition-fast);
  animation: chipInsert 0.22s var(--ease-spring);
}

.active-tile-chip:active {
  cursor: grabbing;
  transform: scale(0.96);
}

.active-tile-chip.dragging {
  opacity: 0.4;
  transform: scale(0.92);
}

.active-tile-chip.drag-over {
  border-color: var(--accent-blue);
  transform: scale(1.06);
}

.active-tile-chip .remove-icon {
  margin-left: 6px;
  font-size: 0.75rem;
  color: var(--text-tertiary);
  opacity: 0.7;
}

@keyframes chipInsert {
  0% { transform: scale(0.7) translateY(8px); opacity: 0; }
  100% { transform: scale(1) translateY(0); opacity: 1; }
}

/* Action controls inside the tray */
.builder-actions {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-left: 6px;
}

.btn-icon-tray {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  font-size: 1.1rem;
  font-weight: 600;
  transition: all var(--transition-fast);
}

.btn-icon-tray:hover {
  background: var(--border-highlight);
  color: var(--text-primary);
  transform: translateY(-1px);
}

.btn-icon-tray:active {
  transform: translateY(1px) scale(0.94);
}

.btn-submit-tray {
  height: 40px;
  padding: 0 16px;
  border-radius: var(--radius-md);
  background: var(--accent-submit-gradient);
  color: #ffffff;
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  display: flex;
  align-items: center;
  gap: 6px;
  box-shadow: 0 2px 8px var(--accent-submit-glow);
  transition: all var(--transition-fast);
}

.btn-submit-tray:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px var(--accent-submit-glow);
}

.btn-submit-tray:active {
  transform: translateY(1px) scale(0.96);
}

.btn-submit-tray:disabled {
  opacity: 0.45;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* ==========================================================================
   THE 4x5 BOARD GRID (20 TILES)
   ========================================================================== */

.board-container {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 10px;
}

.tiles-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-gap: 8px;
  width: 100%;
}

@media (min-width: 480px) {
  .tiles-grid {
    grid-gap: 9px;
  }
}

/* Single Board Tile */
.board-tile {
  aspect-ratio: 1.35 / 1;
  max-height: 56px;
  min-height: 44px;
  background: var(--tile-bg);
  border: 1.5px solid var(--tile-border);
  border-radius: var(--radius-md);
  box-shadow: var(--tile-shadow);
  color: var(--tile-text);
  font-size: 1.12rem;
  font-weight: 700;
  letter-spacing: 0.03em;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  transition: transform var(--transition-fast), background var(--transition-fast), border-color var(--transition-fast), box-shadow var(--transition-fast), opacity var(--transition-fast);
  cursor: pointer;
  outline: none;
}

@media (min-width: 480px) {
  .board-tile {
    font-size: 1.25rem;
  }
}

.board-tile:hover:not(.selected) {
  background: var(--tile-bg-hover);
  border-color: var(--border-highlight);
  box-shadow: var(--tile-shadow-hover);
  transform: translateY(-2px);
}

.board-tile:active:not(.selected) {
  background: var(--tile-bg-active);
  transform: translateY(1px) scale(0.96);
  box-shadow: var(--tile-shadow-selected);
}

/* Selected state: tile is currently in construction tray */
.board-tile.selected {
  opacity: 0.38;
  background: var(--bg-tertiary);
  border-color: var(--border-subtle);
  transform: scale(0.95);
  box-shadow: none;
}

.board-tile.selected::after {
  content: '✓';
  position: absolute;
  top: 4px;
  right: 6px;
  font-size: 0.72rem;
  font-weight: 900;
  color: var(--text-secondary);
}

/* Locked solved Quartile tile state */
.board-tile.locked {
  background: linear-gradient(145deg, var(--tile-bg), var(--bg-tertiary));
  border-color: var(--accent-quartile);
}

.board-tile.locked::before {
  content: '🔒';
  position: absolute;
  top: 4px;
  left: 6px;
  font-size: 0.65rem;
  opacity: 0.8;
}

/* Board tile shuffle animation */
.board-tile.flipping {
  animation: tileFlip 0.4s var(--ease-smooth);
}

@keyframes tileFlip {
  0% { transform: scale(1) rotateY(0); }
  50% { transform: scale(0.85) rotateY(90deg); opacity: 0.5; }
  100% { transform: scale(1) rotateY(0); opacity: 1; }
}

/* Solved Quartile Section Header */
.locked-section-divider {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 4px 6px;
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--accent-quartile);
}