/**
 * Sudoku - Main Styles
 * Mobile-first responsive design
 */

/* Utility */
.hidden { display: none !important; }

/* Reset & Base */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.5;
  min-height: 100vh;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

#app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Typography */
h1, h2, h3 {
  line-height: 1.2;
  font-weight: 600;
}

h1 { font-size: 1.5rem; }
h2 { font-size: 1.25rem; }
h3 { font-size: 1rem; }

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  font-weight: 500;
  border: none;
  border-radius: 0.5rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-primary {
  background-color: var(--color-primary);
  color: var(--color-primary-text);
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--color-primary-hover);
}

.btn-secondary {
  background-color: var(--color-secondary);
  color: var(--color-secondary-text);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--color-secondary-hover);
}

.btn-icon {
  width: 2.5rem;
  height: 2.5rem;
  padding: 0;
  background-color: var(--color-bg-tertiary);
  color: var(--color-text);
  border-radius: 50%;
  font-size: 1.25rem;
}

.btn-icon:hover {
  background-color: var(--color-border);
}

.btn-small {
  padding: 0.25rem 0.5rem;
  font-size: 0.875rem;
}

/* Header */
.header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem;
  background-color: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  box-shadow: var(--shadow-sm);
}

.logo {
  font-size: 1.25rem;
}

.version-badge {
  font-size: 0.6em;
  font-weight: 400;
  color: var(--color-text-secondary);
  vertical-align: middle;
  letter-spacing: 0.02em;
}

.header-actions {
  display: flex;
  gap: 0.5rem;
}

.desktop-actions {
  display: flex;
  gap: 0.5rem;
}

.mobile-only {
  display: none;
}

/* Screens */
.screen {
  flex: 1;
  display: flex;
  flex-direction: column;
  padding: 1rem;
}

.screen.hidden {
  display: none;
}

/* Start Screen */
.start-container {
  max-width: 600px;
  margin: 0 auto;
  width: 100%;
  padding: 2rem 0;
}

.start-container h2 {
  text-align: center;
  margin-bottom: 0.5rem;
}

.tagline {
  text-align: center;
  color: var(--color-text-secondary);
  margin-bottom: 2rem;
}

.start-options {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.option-card {
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: 1rem;
  padding: 1.5rem;
  box-shadow: var(--shadow-md);
  flex: 1;
  display: flex;
  flex-direction: column;
}

.option-card h3 {
  margin-bottom: 0.5rem;
}

.option-card p {
  color: var(--color-text-secondary);
  font-size: 0.875rem;
  margin-bottom: 1rem;
  flex: 1;
}

.difficulty-select {
  margin-bottom: 1rem;
}

.difficulty-select label {
  display: block;
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin-bottom: 0.25rem;
}

.difficulty-select select {
  width: 100%;
  padding: 0.75rem;
  font-size: 1rem;
  border: 1px solid var(--color-border);
  border-radius: 0.5rem;
  background-color: var(--color-bg);
  color: var(--color-text);
}

.option-card .btn {
  width: 100%;
}

/* Game Screen */
.game-container {
  max-width: 500px;
  margin: 0 auto;
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

/* Game Info */
.game-info {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 1rem;
  padding: 0.75rem;
  font-size: 0.875rem;
}

.game-difficulty {
  font-size: 0.875rem;
  text-transform: capitalize;
  color: var(--color-text-secondary);
}

/* Sudoku Board */
.board-wrapper {
  display: flex;
  justify-content: center;
  padding: 0.5rem;
}

.sudoku-board {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 0;
  background-color: var(--board-border);
  border: 3px solid var(--board-border);
  border-radius: 0.5rem;
  overflow: hidden;
  width: 100%;
  max-width: 450px;
  aspect-ratio: 1;
}

/* 4x4 kids grid */
.sudoku-board[data-grid-size="4"] {
  grid-template-columns: repeat(4, 1fr);
  max-width: 300px;
}

/* 6x6 mini grid */
.sudoku-board[data-grid-size="6"] {
  grid-template-columns: repeat(6, 1fr);
  max-width: 380px;
}

.cell {
  position: relative;
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--cell-bg);
  font-size: clamp(1rem, 5vw, 1.75rem);
  font-weight: 500;
  cursor: pointer;
  transition: background-color var(--transition-fast);
  border: 1px solid var(--board-border-thin);
  user-select: none;
}

/* Thicker borders for 3x3 boxes (9x9 grid) */
.sudoku-board[data-grid-size="9"] .cell[data-col="2"],
.sudoku-board[data-grid-size="9"] .cell[data-col="5"] {
  border-right: 2px solid var(--board-border);
}

.sudoku-board[data-grid-size="9"] .cell[data-row="2"],
.sudoku-board[data-grid-size="9"] .cell[data-row="5"] {
  border-bottom: 2px solid var(--board-border);
}

/* Thicker borders for 3x2 boxes (6x6 mini grid) - 3 cols, 2 rows per box */
.sudoku-board[data-grid-size="6"] .cell[data-col="2"] {
  border-right: 2px solid var(--board-border);
}

.sudoku-board[data-grid-size="6"] .cell[data-row="1"],
.sudoku-board[data-grid-size="6"] .cell[data-row="3"] {
  border-bottom: 2px solid var(--board-border);
}

/* Thicker borders for 2x2 boxes (4x4 grid) */
.sudoku-board[data-grid-size="4"] .cell[data-col="1"] {
  border-right: 2px solid var(--board-border);
}

.sudoku-board[data-grid-size="4"] .cell[data-row="1"] {
  border-bottom: 2px solid var(--board-border);
}

.cell:hover:not(.cell-original) {
  background-color: var(--cell-bg-hover);
}

.cell.cell-selected {
  background-color: var(--cell-bg-selected);
}

.cell.cell-highlighted {
  background-color: var(--cell-bg-highlighted);
}

.cell.cell-original {
  background-color: var(--cell-bg-original);
  color: var(--cell-text-original);
  font-weight: 600;
  cursor: default;
}

.cell:not(.cell-original) {
  color: var(--cell-text-player);
}

/* Dot indicator for last move */
.cell.last-move::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 50%;
  transform: translateX(-50%);
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--color-primary);
}

/* Number Pad */
.number-pad {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem;
  /* default: 5 per row — fits 4×4 (5 btns) and 9×9 (10 btns) */
  max-width: calc(5 * 3.5rem + 4 * 0.5rem); /* = 19.5rem */
  margin: 0.5rem auto;
  width: 100%;
  padding: 0.5rem 0;
}

/* 6×6: 7 buttons → 4 per row gives 4+3 (better than 5+2) */
.number-pad[data-gridsize="6"] {
  max-width: calc(4 * 3.5rem + 3 * 0.5rem); /* = 15.5rem */
}

.num-btn {
  width: 3.5rem;
  height: 3.5rem;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  font-weight: 600;
  background-color: var(--color-bg-secondary);
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: 0.5rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.num-btn:hover {
  background-color: var(--color-primary);
  color: var(--color-primary-text);
  border-color: var(--color-primary);
}

.num-btn:active {
  transform: scale(0.95);
}

.num-btn-clear {
  background-color: var(--color-bg-tertiary);
}

.num-btn-clear:hover {
  background-color: var(--color-error);
  border-color: var(--color-error);
}

/* Drag & Drop */
.num-btn.dragging {
  opacity: 0.5;
  transform: scale(0.9);
}

.num-btn[draggable="true"] {
  cursor: grab;
}

.num-btn[draggable="true"]:active {
  cursor: grabbing;
}

.cell.drag-over {
  background-color: var(--cell-bg-selected) !important;
  box-shadow: inset 0 0 0 2px var(--color-primary);
}

/* Touch Drag Ghost (mobile/tablet) */
.touch-drag-ghost {
  position: fixed;
  width: 50px;
  height: 50px;
  background-color: var(--color-primary);
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  font-weight: 700;
  pointer-events: none;
  z-index: 9999;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
  transform: translate(0, 0);
  opacity: 0.9;
}

/* Game Actions */
.game-actions {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
}

.game-timer {
  text-align: center;
  font-size: 1.25rem;
  font-variant-numeric: tabular-nums;
  color: var(--color-text-secondary);
  letter-spacing: 0.05em;
}

/* Modal */
.modal {
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  z-index: 100;
  opacity: 1;
  transition: opacity var(--transition-normal);
}

.modal.hidden {
  display: none;
}

.modal-content {
  background-color: var(--color-bg-secondary);
  border-radius: 1rem;
  padding: 2rem;
  max-width: 500px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  position: relative;
  box-shadow: var(--shadow-lg);
}

.modal-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  width: 2rem;
  height: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--color-text-secondary);
  border-radius: 50%;
}

.modal-close:hover {
  background-color: var(--color-bg-tertiary);
  color: var(--color-text);
}

.modal-content h2 {
  margin-bottom: 1.5rem;
}

.help-section {
  margin-bottom: 1.5rem;
}

.help-section h3 {
  margin-bottom: 0.5rem;
  color: var(--color-primary);
}

.help-section ul {
  padding-left: 1.25rem;
}

.help-section li {
  margin-bottom: 0.25rem;
}

.help-footer {
  margin-bottom: 0;
  padding-top: 1rem;
  border-top: 1px solid var(--color-border);
  text-align: center;
  font-size: 0.875rem;
}

/* Completion Modal */
.completion-content {
  text-align: center;
}

.completion-content h2 {
  font-size: 2rem;
}

.completion-content p {
  color: var(--color-text-secondary);
  margin-bottom: 1.5rem;
}

.completion-time {
  font-size: 1.25rem;
  color: var(--color-text) !important;
}

.completion-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
}

/* Stats Modal */
.stats-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.stat-card {
  background-color: var(--color-bg-tertiary);
  border-radius: 0.5rem;
  padding: 0.75rem 1rem;
  text-align: center;
}

.stat-card .stat-value {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1.1;
}

.stat-card .stat-label {
  font-size: 0.75rem;
  color: var(--color-text-secondary);
  margin-top: 0.2rem;
}

.stats-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}

.stats-table th {
  text-align: left;
  padding: 0.4rem 0.5rem;
  color: var(--color-text-secondary);
  font-weight: 600;
  border-bottom: 1px solid var(--color-border);
}

.stats-table td {
  padding: 0.4rem 0.5rem;
  border-bottom: 1px solid var(--color-border);
}

.stats-table tr:last-child td {
  border-bottom: none;
}

.stats-empty {
  text-align: center;
  color: var(--color-text-secondary);
  padding: 2rem 0;
}

.stats-clear-btn {
  margin-top: 0.5rem;
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  background: none;
  border: 1px solid var(--color-border);
  border-radius: 0.375rem;
  padding: 0.3rem 0.75rem;
  cursor: pointer;
}

.stats-clear-btn:hover {
  background-color: var(--color-bg-tertiary);
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 1rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  z-index: 200;
  width: max-content;
  max-width: calc(100vw - 2rem);
}

.toast {
  padding: 0.75rem 1rem;
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: 0.5rem;
  box-shadow: var(--shadow-lg);
  animation: slideUp 0.3s ease;
  width: 100%;
  text-align: center;
}

.toast.toast-success {
  border-color: var(--color-success);
  background-color: color-mix(in srgb, var(--color-success) 10%, var(--color-bg-secondary));
}

.toast.toast-error {
  border-color: var(--color-error);
  background-color: color-mix(in srgb, var(--color-error) 10%, var(--color-bg-secondary));
}

/* ============================================================
   Menu Dropdown
   ============================================================ */
.menu-wrapper {
  position: relative;
}

.menu-dropdown {
  position: absolute;
  right: 0;
  top: calc(100% + 0.5rem);
  background-color: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: 0.5rem;
  box-shadow: var(--shadow-lg);
  min-width: 180px;
  z-index: 150;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.menu-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  background: none;
  border: none;
  border-bottom: 1px solid var(--color-border);
  cursor: pointer;
  color: var(--color-text);
  text-align: left;
  font-size: 0.95rem;
  text-decoration: none;
  width: 100%;
  font-family: inherit;
}

.menu-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.25rem;
  height: 1.25rem;
  font-size: 1.1rem;
  flex-shrink: 0;
  line-height: 1;
}

.menu-icon svg {
  width: 1.1rem;
  height: 1.1rem;
}

.menu-item:last-child {
  border-bottom: none;
}

.menu-item:hover {
  background-color: var(--color-bg-tertiary);
}

/* ============================================================
   Settings Modal
   ============================================================ */
.settings-section {
  padding: 0.5rem 0;
}

.setting-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--color-border);
}

.setting-row:last-child {
  border-bottom: none;
}

.setting-label {
  font-size: 0.95rem;
}

/* Toggle switch */
.toggle-switch {
  position: relative;
  display: inline-block;
  width: 3rem;
  height: 1.5rem;
  cursor: pointer;
  flex-shrink: 0;
}

.toggle-switch input {
  opacity: 0;
  width: 0;
  height: 0;
  position: absolute;
}

.toggle-track {
  position: absolute;
  inset: 0;
  background-color: var(--color-border);
  border-radius: 1.5rem;
  transition: background-color 0.2s;
}

.toggle-track::before {
  content: '';
  position: absolute;
  width: 1.1rem;
  height: 1.1rem;
  left: 0.2rem;
  top: 50%;
  transform: translateY(-50%);
  background-color: #fff;
  border-radius: 50%;
  transition: left 0.2s;
}

.toggle-switch input:checked + .toggle-track {
  background-color: var(--color-primary);
}

.toggle-switch input:checked + .toggle-track::before {
  left: calc(100% - 1.3rem);
}

@keyframes slideUp {
  from {
    transform: translateY(100%);
    opacity: 0;
  }
  to {
    transform: translateY(0);
    opacity: 1;
  }
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  10%, 30%, 50%, 70%, 90% { transform: translateX(-4px); }
  20%, 40%, 60%, 80% { transform: translateX(4px); }
}

.cell-error {
  animation: shake 0.5s ease-in-out;
  background-color: color-mix(in srgb, var(--color-error) 30%, transparent) !important;
}

/* Responsive - Mobile only */
@media (max-width: 639px) {
  .desktop-actions {
    display: none;
  }
  .mobile-only {
    display: block;
  }
}

/* Responsive - Tablet and up */
@media (min-width: 640px) {
  h1 { font-size: 1.75rem; }
  h2 { font-size: 1.5rem; }

  .start-options {
    flex-direction: row;
  }

  .option-card {
    flex: 1;
  }

  .number-pad {
    max-width: calc(5 * 4rem + 4 * 0.5rem); /* 22rem — fits 5 per row */
  }

  .number-pad[data-gridsize="6"] {
    max-width: calc(4 * 4rem + 3 * 0.5rem); /* 17.5rem — forces 4 per row */
  }

  .num-btn {
    width: 4rem;
    height: 4rem;
    padding: 0;
  }
}

/* Responsive - Desktop */
@media (min-width: 1024px) {
  .header {
    padding: 1rem 2rem;
  }

  .screen {
    padding: 2rem;
  }

  .logo {
    font-size: 1.5rem;
  }
}

/* Focus styles for accessibility */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.cell:focus-visible {
  outline-offset: -2px;
}

/* Print styles */
@media print {
  .header, .number-pad, .game-actions, .game-info {
    display: none;
  }

  .sudoku-board {
    max-width: 100%;
    border-color: #000;
  }

  .cell {
    border-color: #999;
    color: #000 !important;
  }

  .cell.cell-original {
    background-color: #eee !important;
  }
}