/* Controls */
.controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 0.75rem;
  padding: 1rem 0;
}

.controls-left {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.difficulty-group {
  display: flex;
  gap: 0.25rem;
}

.difficulty-btn.active {
  background-color: var(--accent-purple);
  color: #fff;
}

.timer {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.25rem;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

.btn-small {
  padding: 0.3rem 0.4rem;
}

/* Sudoku Grid */
.sudoku-grid {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 1px;
  background-color: var(--bg-primary);
  border: 2px solid var(--fg-primary);
  border-radius: 4px;
  width: min(680px, 100%);
  margin: 0 auto;
  aspect-ratio: 1;
  overflow: hidden;
}

.sudoku-grid.loaded {
  background-color: var(--fg-secondary);
}

.cell {
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--bg-primary);
  font-size: clamp(1.2rem, 4vw, 2rem);
  font-weight: 600;
  cursor: pointer;
  position: relative;
  transition: background-color 0.15s;
  user-select: none;
  min-height: 0;
  aspect-ratio: 1;
}

/* Box borders — thicker lines every 3 cells */
.cell[data-col="2"],
.cell[data-col="5"] {
  border-right: 2px solid var(--fg-primary);
}

.cell[data-row="2"],
.cell[data-row="5"] {
  border-bottom: 2px solid var(--fg-primary);
}

/* Given (pre-filled) cells */
.cell.given {
  color: var(--fg-primary);
  font-weight: 700;
}

/* User-entered cells */
.cell.user-input {
  color: var(--accent-purple);
}

/* Selected cell */
.cell.selected {
  background-color: var(--bg-selection);
  box-shadow: inset 0 0 0 2.5px var(--accent-purple);
  z-index: 1;
}

/* Highlight cells in same row/col/box */
.cell.highlighted {
  background-color: var(--bg-secondary);
}

/* Same number highlight */
.cell.same-number {
  background-color: var(--highlight-same);
  color: var(--highlight-same-fg);
  font-weight: 800;
}

/* Error state */
.cell.error {
  color: var(--accent-red);
  background-color: var(--highlight-error);
}


/* Pencil marks */
.pencil-marks {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  width: 100%;
  height: 100%;
  position: absolute;
  inset: 0;
  padding: 2px;
}

.pencil-marks span {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: clamp(0.4rem, 1.5vw, 0.6rem);
  font-weight: 400;
  color: var(--fg-secondary);
  line-height: 1;
}

.pencil-marks span.mark-highlighted {
  color: var(--accent-purple);
  font-weight: 700;
}

/* Actions */
.actions {
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  padding: 1rem 0;
  flex-wrap: wrap;
}

/* Number pad */
.numpad {
  display: flex;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.5rem 0 1rem;
  flex-wrap: wrap;
}

.numpad-btn {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--bg-secondary);
  color: var(--fg-primary);
  border: none;
  border-radius: var(--radius);
  font-size: 1.2rem;
  font-weight: 700;
  cursor: pointer;
  transition: background-color 0.15s, transform 0.1s;
}

.numpad-btn:hover {
  background-color: var(--accent-purple);
  color: #fff;
}

.numpad-btn:active {
  transform: scale(0.93);
}

.numpad-btn.completed {
  opacity: 0.3;
  pointer-events: none;
}

/* Toggle button active indicator */
#pencil-btn.active,
#check-btn.active {
  background-color: var(--accent-purple);
  color: #fff;
}

/* Timer paused state */
.timer.paused #timer-display {
  opacity: 0.5;
}


/* Responsive */
@media (max-width: 500px) {
  .sudoku-grid {
    max-width: 100%;
  }

  .actions {
    gap: 0.35rem;
  }

  .actions .btn {
    padding: 0.4rem 0.6rem;
    font-size: 0.8rem;
  }

  .numpad-btn {
    width: 36px;
    height: 36px;
    font-size: 1rem;
  }
}

/* Desktop: tighten spacing for scaled layout */
@media (min-width: 1024px) {
  .controls {
    padding: 0.5rem 0;
  }

  .actions {
    padding: 0.5rem 0;
  }

  .numpad {
    padding: 0.25rem 0 0.5rem;
  }
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  .cell,
  .numpad-btn,
  .btn {
    transition: none;
  }
}