/* Sudoku Styles */

.difficulty-bar {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}

.diff-btn {
  padding: 0.4rem 1.1rem;
  border: 1px solid var(--bg-glass-border);
  background: var(--bg-glass);
  color: var(--text-secondary);
  border-radius: var(--radius-full);
  font-family: var(--font-primary);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition-base);
}

.diff-btn.active {
  background: rgba(59, 130, 246, 0.15);
  border-color: rgba(59, 130, 246, 0.3);
  color: #3b82f6;
}

.diff-btn:hover:not(.active) {
  background: var(--bg-card-hover);
}

.board-container { position: relative; }

.sudoku-board {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 0;
  width: min(380px, 90vw);
  aspect-ratio: 1;
  background: rgba(255, 255, 255, 0.06);
  border: 2px solid rgba(255, 255, 255, 0.15);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.sdk-cell {
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-size: 1.3rem;
  font-weight: 600;
  cursor: pointer;
  background: rgba(255, 255, 255, 0.02);
  border: 0.5px solid rgba(255, 255, 255, 0.05);
  transition: background 0.12s;
  -webkit-tap-highlight-color: transparent;
  color: var(--text-primary);
}

/* 3x3 box borders */
.sdk-cell[data-col="2"],
.sdk-cell[data-col="5"] {
  border-right: 2px solid rgba(255, 255, 255, 0.15);
}

.sdk-cell[data-row="2"],
.sdk-cell[data-row="5"] {
  border-bottom: 2px solid rgba(255, 255, 255, 0.15);
}

.sdk-cell:hover {
  background: rgba(255, 255, 255, 0.06);
}

.sdk-cell.selected {
  background: rgba(59, 130, 246, 0.15) !important;
  box-shadow: inset 0 0 0 2px rgba(59, 130, 246, 0.4);
}

.sdk-cell.highlight {
  background: rgba(59, 130, 246, 0.06);
}

.sdk-cell.given {
  color: var(--text-secondary);
  cursor: default;
}

.sdk-cell.user {
  color: #3b82f6;
}

.sdk-cell.error {
  color: #ef4444 !important;
  background: rgba(239, 68, 68, 0.08);
}

.sdk-cell.same-num {
  background: rgba(59, 130, 246, 0.1);
}

/* Number pad */
.num-pad {
  display: flex;
  gap: 0.5rem;
  margin-top: 1.25rem;
  flex-wrap: wrap;
  justify-content: center;
}

.num-btn {
  width: 44px;
  height: 44px;
  border: 1px solid rgba(255, 255, 255, 0.08);
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-secondary);
  border-radius: var(--radius-md);
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
}

.num-btn:hover {
  background: rgba(59, 130, 246, 0.15);
  border-color: rgba(59, 130, 246, 0.3);
  color: #3b82f6;
}

.num-btn:active {
  transform: scale(0.92);
}

.erase-btn {
  color: #ef4444;
}

/* Overlay */
.sdk-overlay {
  position: absolute;
  inset: 0;
  background: rgba(10, 10, 15, 0.88);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 10;
  transition: var(--transition-base);
}

.sdk-overlay.hidden {
  opacity: 0; visibility: hidden; pointer-events: none;
}

.sdk-overlay-content { text-align: center; }
.sdk-overlay-icon { font-size: 3rem; margin-bottom: 0.75rem; }

.sdk-overlay-content h2 {
  font-family: var(--font-display);
  font-size: 1.8rem;
  font-weight: 800;
  margin-bottom: 0.4rem;
}

.sdk-overlay-content p {
  color: var(--text-secondary);
  margin-bottom: 1.25rem;
}

@media (max-width: 480px) {
  .sdk-cell { font-size: 1rem; }
  .num-btn { width: 38px; height: 38px; font-size: 0.95rem; }
}