:root,
[data-theme="dark"] {
  --bg-primary: #1a1a2e;
  --bg-secondary: #16213e;
  --bg-surface: #0f3460;
  --text-primary: #e0e0e0;
  --text-secondary: #a0a0b0;
  --accent: #e94560;
  --accent-hover: #ff6b81;
  --cell-hidden: #40406a;
  --cell-hidden-border-light: #58588a;
  --cell-hidden-border-dark: #2a2a48;
  --cell-revealed: #0e0e1c;
  --cell-marked: #5a4a28;
  --cell-mine: #6a1a1a;
  --cell-selected: #e94560;
  --cell-dark: #08080f;
  --cell-border: #3a3a5a;
  --grid-gap: #121220;
  --btn-open: #2ecc71;
  --btn-open-hover: #27ae60;
  --btn-mark: #f39c12;
  --btn-mark-hover: #e67e22;

  --num-1: #6ab0f0;
  --num-2: #80d880;
  --num-3: #f07070;
  --num-4: #a090e0;
  --num-5: #e06060;
  --num-6: #60d0d0;
  --num-7: #909090;
  --num-8: #c0c0c0;
}

[data-theme="light"] {
  --bg-primary: #e0e0ea;
  --bg-secondary: #ffffff;
  --bg-surface: #d8d8e5;
  --text-primary: #1a1a2e;
  --text-secondary: #55556a;
  --accent: #d63050;
  --accent-hover: #b82545;
  --cell-hidden: #a8adc0;
  --cell-hidden-border-light: #c0c5d5;
  --cell-hidden-border-dark: #8a8fa0;
  --cell-revealed: #f0f0f8;
  --cell-marked: #f0d898;
  --cell-mine: #f5b0b0;
  --cell-selected: #d63050;
  --cell-dark: #90909f;
  --cell-border: #b0b0c5;
  --grid-gap: #c8c8d5;
  --btn-open: #27ae60;
  --btn-open-hover: #219a52;
  --btn-mark: #e67e22;
  --btn-mark-hover: #cf6d17;

  --num-1: #1a55a0;
  --num-2: #1e7a1e;
  --num-3: #b02020;
  --num-4: #5030a0;
  --num-5: #901515;
  --num-6: #107070;
  --num-7: #303030;
  --num-8: #555555;
}

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

html, body {
  height: 100%;
  overflow: hidden;
  touch-action: manipulation;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  -webkit-user-select: none;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

/* Screen management */
.screen {
  display: none;
  height: 100%;
}

.screen.active {
  display: flex;
  flex-direction: column;
}

/* ===== MENU SCREEN ===== */
.menu-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex: 1;
  padding: 2rem 1.5rem;
  gap: 1.5rem;
}

.menu-title {
  font-size: 1.8rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  text-align: center;
  background: linear-gradient(135deg, var(--accent), #ff9a76);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.mode-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  width: 100%;
  max-width: 340px;
  margin-top: 1rem;
}

.mode-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.15rem;
  padding: 0.7rem 1rem;
  background: var(--bg-secondary);
  border: 2px solid var(--cell-border);
  border-radius: 12px;
  color: var(--text-primary);
  cursor: pointer;
  transition: border-color 0.2s, transform 0.1s;
  min-height: 44px;
}

.mode-btn:hover, .mode-btn:focus-visible {
  border-color: var(--accent);
  transform: translateY(-1px);
}

.mode-btn:active {
  transform: translateY(0);
}

.mode-name {
  font-size: 1.15rem;
  font-weight: 700;
}

.mode-desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
}

.menu-help-btn {
  border-style: dashed;
}

/* ===== GAME SCREEN ===== */
.game-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 0.75rem;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--cell-border);
  flex-shrink: 0;
}

.header-btn {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background: none;
  border: 1px solid var(--cell-border);
  border-radius: 8px;
  color: var(--text-primary);
  font-size: 1.4rem;
  cursor: pointer;
  transition: background 0.15s;
}

.header-btn:hover, .header-btn:focus-visible {
  background: var(--bg-surface);
}

.header-right {
  display: flex;
  gap: 0.4rem;
}

.game-info {
  display: flex;
  gap: 1.5rem;
  font-size: 1.1rem;
  font-weight: 600;
}

.info-item {
  display: flex;
  align-items: center;
  gap: 0.3rem;
}

/* Header result banners */
.header-banner {
  font-size: 1.2rem;
  font-weight: 800;
  text-align: center;
}

.header-banner.hidden {
  display: none;
}

.header-banner-win {
  color: var(--btn-open);
}

.header-banner-lose {
  color: var(--accent);
}

/* ===== BOARD ===== */
#board-container {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem 0.5rem 0.5rem 0.5rem;
  overflow: hidden;
}

.board-grid {
  display: grid;
  gap: 2px;
  background: var(--grid-gap);
  border: 2px solid var(--cell-border);
  border-radius: 4px;
}

.cell {
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--cell-hidden);
  border: none;
  border-top: 2px solid var(--cell-hidden-border-light);
  border-left: 2px solid var(--cell-hidden-border-light);
  border-right: 2px solid var(--cell-hidden-border-dark);
  border-bottom: 2px solid var(--cell-hidden-border-dark);
  color: var(--text-primary);
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.1s;
  position: relative;
  padding: 0;
  min-width: 0;
  min-height: 0;
}

.cell:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
  z-index: 1;
}

.cell.selected {
  outline: 3px solid var(--cell-selected);
  outline-offset: -3px;
  z-index: 2;
}

.cell.revealed {
  background: var(--cell-revealed);
  border-color: var(--cell-revealed);
  cursor: default;
}

.cell.marked {
  background: var(--cell-marked);
}

.cell.questioned {
  background: var(--cell-hidden);
}

.cell.mine-exploded {
  background: var(--cell-mine);
  border-color: var(--cell-mine);
}

.cell.dark {
  background: var(--cell-dark);
  border-color: var(--cell-dark);
  cursor: default;
}

.cell.dark .cell-content {
  visibility: hidden;
}

.cell-content {
  pointer-events: none;
}

/* Number colors */
.cell[data-number="1"] .cell-content { color: var(--num-1); }
.cell[data-number="2"] .cell-content { color: var(--num-2); }
.cell[data-number="3"] .cell-content { color: var(--num-3); }
.cell[data-number="4"] .cell-content { color: var(--num-4); }
.cell[data-number="5"] .cell-content { color: var(--num-5); }
.cell[data-number="6"] .cell-content { color: var(--num-6); }
.cell[data-number="7"] .cell-content { color: var(--num-7); }
.cell[data-number="8"] .cell-content { color: var(--num-8); }

/* Screen reader only text */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

/* ===== FOOTER ===== */
.game-footer {
  padding: 0.6rem 0.75rem;
  background: var(--bg-secondary);
  border-top: 1px solid var(--cell-border);
  flex-shrink: 0;
}

.action-buttons {
  display: flex;
  gap: 0.75rem;
}

.action-btn {
  flex: 1;
  padding: 0.75rem;
  border: none;
  border-radius: 8px;
  font-size: 1.1rem;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.15s, opacity 0.15s;
  min-height: 44px;
}

.action-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.btn-open {
  background: var(--btn-open);
  color: #fff;
}

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

.btn-mark {
  background: var(--btn-mark);
  color: #fff;
}

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

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

.btn-question:hover:not(:disabled) {
  background: var(--cell-border);
}

/* ===== KEYBOARD NAV ===== */
.board-grid:focus-within .cell:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: -2px;
}

/* ===== MENU SETTINGS ===== */
.menu-settings {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.6rem;
  margin-top: 1.5rem;
  align-items: center;
}

.lang-select {
  padding: 0.6rem 0.8rem;
  background: var(--bg-secondary);
  border: 1px solid var(--cell-border);
  border-radius: 8px;
  color: var(--text-secondary);
  font-size: 0.9rem;
  cursor: pointer;
  min-height: 44px;
  transition: border-color 0.2s;
  -webkit-appearance: none;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6'%3E%3Cpath d='M0 0l5 6 5-6z' fill='%23a0a0b0'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.6rem center;
  padding-right: 2rem;
}

.lang-select:hover, .lang-select:focus-visible {
  border-color: var(--accent);
}

.lang-select option {
  background: var(--bg-secondary);
  color: var(--text-primary);
}

.theme-toggle {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.6rem 1.2rem;
  background: var(--bg-secondary);
  border: 1px solid var(--cell-border);
  border-radius: 8px;
  color: var(--text-secondary);
  font-size: 0.9rem;
  cursor: pointer;
  transition: border-color 0.2s;
  min-height: 44px;
}

.theme-toggle:hover, .theme-toggle:focus-visible {
  border-color: var(--accent);
}

/* ===== HELP SCREEN ===== */
.help-header-title {
  font-size: 1.1rem;
  font-weight: 700;
  text-align: center;
}

.help-content {
  flex: 1;
  overflow-y: auto;
  padding: 1.5rem 1.25rem;
}

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

.help-section-title {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 0.6rem;
  color: var(--accent);
}

.help-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.help-list li {
  font-size: 0.95rem;
  line-height: 1.5;
  color: var(--text-primary);
  padding: 0.5rem 0.75rem;
  background: var(--bg-secondary);
  border-radius: 8px;
  border: 1px solid var(--cell-border);
}

/* ===== RESPONSIVE ===== */
@media (min-width: 500px) {
  .menu-container {
    padding: 3rem 2rem;
  }

  .mode-list {
    max-width: 400px;
  }
}

/* Game screen needs position relative for overlay */
#game-screen {
  position: relative;
}