/* ===================== 全局变量与重置 ===================== */
:root {
  --color-bg: #f5f5f5;
  --color-white: #ffffff;
  --color-text: #333333;
  --color-text-light: #888888;
  --color-primary: #4a90d9;
  --color-primary-dark: #357abd;
  --color-user: #4a90d9;
  --color-fixed: #333333;
  --color-error: #e74c3c;
  --color-hint: #27ae60;
  --color-selected: #bbdefb;
  --color-related: #e8f0fe;
  --color-same-num: #c8e6c9;
  --color-border: #b0b0b0;
  --color-border-thick: #333333;
  --color-grid-bg: #ffffff;
  --color-btn: #4a90d9;
  --color-btn-hover: #357abd;
  --color-btn-text: #ffffff;
  --color-btn-disabled: #cccccc;
  --border-thin: 1px solid var(--color-border);
  --border-thick: 2px solid var(--color-border-thick);
  --cell-size: min(10vw, 52px);
  --font-size-cell: min(5vw, 24px);
  --radius: 10px;
  --shadow: 0 2px 12px rgba(0,0,0,0.08);
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

.hidden {
  display: none !important;
}

/* ===================== 首页 ===================== */
.home-page {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 20px;
  width: 100%;
  max-width: 480px;
  margin: 0 auto;
}

.home-title {
  font-size: 2.2rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--color-primary);
  letter-spacing: 4px;
}

.home-subtitle {
  font-size: 0.95rem;
  color: var(--color-text-light);
  margin-bottom: 40px;
}

.difficulty-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  width: 100%;
  max-width: 300px;
}

.difficulty-btn {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 24px;
  border: 2px solid #e0e0e0;
  border-radius: var(--radius);
  background: var(--color-white);
  font-size: 1.05rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow);
}

.difficulty-btn:hover {
  border-color: var(--color-primary);
  background: var(--color-related);
  transform: translateY(-1px);
}

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

.difficulty-btn .diff-name {
  font-weight: 600;
}

.difficulty-btn .diff-blanks {
  font-size: 0.85rem;
  color: var(--color-text-light);
}

.continue-btn {
  margin-top: 24px;
  padding: 12px 40px;
  border: none;
  border-radius: var(--radius);
  background: var(--color-hint);
  color: var(--color-white);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow);
}

.continue-btn:hover {
  background: #219a52;
  transform: translateY(-1px);
}

/* ===================== 游戏页 ===================== */
.game-page {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: 100vh;
  padding: 16px 12px 24px;
  width: 100%;
  max-width: 480px;
  margin: 0 auto;
}

/* ========== 顶部信息栏 ========== */
.info-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: 400px;
  padding: 10px 8px;
  margin-bottom: 12px;
  background: var(--color-white);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  font-size: 0.9rem;
  gap: 6px;
}

.pause-btn {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 6px 14px;
  border: 1px solid var(--color-border);
  border-radius: 6px;
  background: var(--color-white);
  font-size: 0.85rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.pause-btn:hover {
  background: var(--color-related);
}

.pause-icon {
  width: 16px;
  height: 16px;
  display: flex;
  gap: 2px;
}

.pause-icon span {
  width: 4px;
  height: 14px;
  background: var(--color-text);
  border-radius: 1px;
}

.info-item {
  display: flex;
  align-items: center;
  gap: 4px;
  white-space: nowrap;
}

.info-label {
  color: var(--color-text-light);
  font-size: 0.8rem;
}

.info-value {
  font-weight: 600;
  font-size: 0.9rem;
}

.info-value.error {
  color: var(--color-error);
}

/* ========== 棋盘 ========== */
.board-container {
  background: var(--color-white);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 6px;
  margin-bottom: 16px;
  position: relative;
}

.board {
  display: grid;
  grid-template-columns: repeat(9, var(--cell-size));
  grid-template-rows: repeat(9, var(--cell-size));
  border: var(--border-thick);
  border-radius: 4px;
  overflow: hidden;
  position: relative;
}

.cell {
  display: flex;
  align-items: center;
  justify-content: center;
  border-right: var(--border-thin);
  border-bottom: var(--border-thin);
  cursor: pointer;
  position: relative;
  transition: background-color var(--transition-fast);
  background: var(--color-grid-bg);
}

/* 3x3宫格粗边框 */
.cell:nth-child(9n+3),
.cell:nth-child(9n+6) {
  border-right: var(--border-thick);
}

.cell:nth-child(n+19):nth-child(-n+27),
.cell:nth-child(n+46):nth-child(-n+54) {
  border-bottom: var(--border-thick);
}

/* 去掉最后一列右边框和最后一行底边框 */
.cell:nth-child(9n) {
  border-right: none;
}
.cell:nth-child(n+73) {
  border-bottom: none;
}

.cell-value {
  font-size: var(--font-size-cell);
  font-weight: 500;
  line-height: 1;
  transition: all var(--transition-fast);
}

/* 固定数字 */
.cell.fixed .cell-value {
  color: var(--color-fixed);
  font-weight: 700;
}

/* 用户输入数字 */
.cell.user-input .cell-value {
  color: var(--color-user);
}

/* 错误数字 */
.cell.error .cell-value {
  color: var(--color-error) !important;
  font-weight: 700;
}

.cell.error {
  background: #fde8e8 !important;
}

/* 提示填入 */
.cell.hinted .cell-value {
  color: var(--color-hint) !important;
}

/* 选中格 */
.cell.selected {
  background: var(--color-selected) !important;
}

/* 同行/同列/同宫高亮 */
.cell.related {
  background: var(--color-related);
}

/* 相同数字高亮 */
.cell.same-num {
  background: var(--color-same-num);
}

/* ========== 底部功能区 ========== */
.action-bar {
  display: flex;
  gap: 16px;
  margin-bottom: 12px;
  width: 100%;
  max-width: 400px;
  justify-content: center;
}

.action-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 10px 28px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  background: var(--color-white);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 0.85rem;
  min-width: 80px;
}

.action-btn:hover {
  background: var(--color-related);
  border-color: var(--color-primary);
}

.action-btn:active {
  transform: scale(0.96);
}

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

.action-btn .btn-icon {
  font-size: 1.3rem;
}

.action-btn .btn-label {
  display: flex;
  align-items: center;
  gap: 4px;
  font-weight: 500;
}

.action-btn .btn-count {
  font-size: 0.75rem;
  color: var(--color-text-light);
  background: #f0f0f0;
  padding: 1px 6px;
  border-radius: 10px;
}

/* ========== 数字输入区 ========== */
.number-pad {
  display: flex;
  gap: 4px;
  width: 100%;
  max-width: 400px;
  justify-content: center;
  flex-wrap: nowrap;
}

.num-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex: 1 1 auto;
  aspect-ratio: 1;
  border: 1px solid #e0e0e0;
  border-radius: 8px;
  background: var(--color-white);
  cursor: pointer;
  transition: all 0.3s ease;
  box-shadow: 0 1px 3px rgba(0,0,0,0.06);
  padding: 2px;
  min-width: 0;
}

.num-btn:hover {
  background: var(--color-selected);
  border-color: var(--color-primary);
  transform: translateY(-1px);
}

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

.num-btn.disabled {
  flex: 0 0 0;
  opacity: 0;
  pointer-events: none;
  padding: 0;
  border: none;
  margin: 0;
  overflow: hidden;
  min-width: 0;
}

.num-btn .num-value {
  font-size: min(4.5vw, 22px);
  font-weight: 700;
  color: var(--color-user);
  line-height: 1;
}

.num-btn .num-count {
  font-size: min(2.5vw, 11px);
  color: var(--color-text-light);
  line-height: 1;
  margin-top: 1px;
}

/* ===================== 暂停遮罩 ===================== */
.overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  backdrop-filter: blur(4px);
  animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.pause-menu {
  background: var(--color-white);
  border-radius: 16px;
  padding: 32px 28px;
  width: 90%;
  max-width: 320px;
  box-shadow: 0 8px 32px rgba(0,0,0,0.15);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  animation: slideUp 0.25s ease;
}

@keyframes slideUp {
  from { transform: translateY(20px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

.pause-title {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.pause-menu .menu-btn {
  width: 100%;
  padding: 12px;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.pause-menu .menu-btn:hover {
  transform: translateY(-1px);
}

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

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

.restart-btn {
  background: #f0f0f0;
  color: var(--color-text);
}

.new-game-btn {
  background: #f0f0f0;
  color: var(--color-text);
}

.home-btn {
  background: none;
  color: var(--color-error);
  border: 1px solid #e0e0e0 !important;
}

/* ===================== 胜利/失败弹窗 ===================== */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 200;
  backdrop-filter: blur(4px);
  animation: fadeIn 0.2s ease;
}

.modal-content {
  background: var(--color-white);
  border-radius: 16px;
  padding: 36px 28px;
  width: 90%;
  max-width: 320px;
  box-shadow: 0 8px 32px rgba(0,0,0,0.15);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  animation: slideUp 0.25s ease;
  text-align: center;
}

.modal-icon {
  font-size: 3rem;
  margin-bottom: 4px;
}

.modal-title {
  font-size: 1.4rem;
  font-weight: 700;
}

.modal-stats {
  display: flex;
  gap: 20px;
  margin: 8px 0;
}

.modal-stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}

.stat-value {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--color-primary);
}

.stat-label {
  font-size: 0.8rem;
  color: var(--color-text-light);
}

.modal-info {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin: 4px 0;
}

.modal-btns {
  display: flex;
  gap: 12px;
  width: 100%;
  margin-top: 8px;
}

.modal-btn {
  flex: 1;
  padding: 12px 8px;
  border: none;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.modal-btn:hover {
  transform: translateY(-1px);
}

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

.modal-btn.secondary {
  background: #f0f0f0;
  color: var(--color-text);
}

/* ===================== Toast ===================== */
#toast {
  position: fixed;
  bottom: 80px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: rgba(0, 0, 0, 0.75);
  color: #fff;
  padding: 10px 24px;
  border-radius: 20px;
  font-size: 0.9rem;
  z-index: 300;
  opacity: 0;
  pointer-events: none;
  transition: all 0.3s ease;
}

#toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ===================== 棋盘暂停遮罩 ===================== */
.board-container.paused .board {
  filter: blur(8px);
  pointer-events: none;
}

.board-container.paused::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(255, 255, 255, 0.3);
  border-radius: var(--radius);
}

/* ===================== 数字填入动画 ===================== */
@keyframes popIn {
  0% { transform: scale(0.5); opacity: 0.5; }
  70% { transform: scale(1.15); }
  100% { transform: scale(1); opacity: 1; }
}

.cell.pop .cell-value {
  animation: popIn 0.25s ease;
}

/* ===================== 加载遮罩 ===================== */
.loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(255, 255, 255, 0.85);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 500;
  backdrop-filter: blur(2px);
}

.loading-spinner {
  width: 40px;
  height: 40px;
  border: 4px solid #e0e0e0;
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.loading-text {
  margin-top: 16px;
  font-size: 1rem;
  color: var(--color-text);
  font-weight: 500;
}

/* ===================== 响应式 ===================== */
@media (max-width: 420px) {
  :root {
    --cell-size: min(10.5vw, 42px);
    --font-size-cell: min(5.5vw, 20px);
  }

  .home-title {
    font-size: 1.8rem;
  }

  .info-bar {
    font-size: 0.8rem;
    padding: 8px 6px;
  }

  .action-btn {
    padding: 8px 20px;
    min-width: 70px;
  }

  .num-btn {
    border-radius: 6px;
  }

  .modal-content {
    padding: 28px 20px;
  }
}

@media (min-width: 500px) {
  :root {
    --cell-size: 52px;
    --font-size-cell: 24px;
  }
}

/* 减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01s !important;
    transition-duration: 0.01s !important;
  }
}