:root {
  /* 尺寸变量 */
  --cell-size: 44px;
  --cell-size-mobile: 36px;
  --board-width: calc(var(--cell-size) * 9 + 6px); /* 9格 + 边框微调 */
  --content-max-width: 500px; /* 统一容器宽度 */

  /* 浅色主题 */
  --bg-primary: #f6f8fa;
  --bg-board: #ffffff;
  --bg-prefilled: #eef2f5; /*稍微偏蓝灰一点更现代*/
  --bg-records: #ffffff;
  --bg-button: #ffffff;
  --bg-input: #ffffff;
  --text-primary: #24292f;
  --text-secondary: #57606a;
  --border-normal: #d0d7de;
  --border-thick: #24292f;
  --border-focus: #0969da;
  --conflict-bg: #ffebe9;
  --conflict-text: #cf222e;
  --caret-color: #0969da;
  --btn-hover: #f3f4f6;
  --shadow-card: 0 3px 10px rgba(0,0,0,0.05);
}

@media (prefers-color-scheme: dark) {
  :root {
    /* 暗色主题 */
    --bg-primary: #0d1117;
    --bg-board: #161b22;
    --bg-prefilled: #21262d;
    --bg-records: #161b22;
    --bg-button: #21262d;
    --bg-input: #0d1117;
    --text-primary: #c9d1d9;
    --text-secondary: #8b949e;
    --border-normal: #30363d;
    --border-thick: #8b949e;
    --border-focus: #58a6ff;
    --conflict-bg: #490202;
    --conflict-text: #ff7b72;
    --caret-color: #58a6ff;
    --btn-hover: #30363d;
    --shadow-card: none;
  }
}

* { box-sizing: border-box; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 20px 10px;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
}

/* 主容器：统一所有内容的宽度 */
.main-container {
  width: 100%;
  max-width: var(--content-max-width);
  display: flex;
  flex-direction: column;
  gap: 16px;
}

/* 头部 */
.header-section {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 10px;
}

h1 {
  font-size: 26px;
  margin: 0;
  font-weight: 700;
}

/* 登录区域 */
.login-area {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

/* 通用控件样式 (Input, Select, Button) */
.form-control, .btn {
  height: 36px; /* 统一高度 */
  padding: 0 12px;
  font-size: 14px;
  border: 1px solid var(--border-normal);
  border-radius: 6px;
  background: var(--bg-button);
  color: var(--text-primary);
  transition: all 0.2s;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.form-control {
  background: var(--bg-input);
  width: 200px; /* 默认宽度 */
}

.form-control:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 2px rgba(9, 105, 218, 0.2);
}

.btn {
  cursor: pointer;
  font-weight: 600;
}

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

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

.btn-danger {
  color: #cf222e;
  border-color: var(--border-normal);
}
.btn-danger:hover {
  background: #fff0f0;
  border-color: #cf222e;
}

.btn-sm {
  height: 28px;
  padding: 0 8px;
  font-size: 12px;
}

.logout-link {
  font-size: 13px;
  color: var(--text-secondary);
  text-decoration: underline;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
  margin-left: 5px;
}
.logout-link:hover { color: var(--caret-color); }

/* 游戏控制栏 */
.controls-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
  padding: 4px 0;
}

.controls-group {
  display: flex;
  gap: 8px;
}

/* 计时器 */
.timer-display {
  font-family: "SF Mono", "Monaco", monospace;
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
  text-align: center;
  width: 100%;
  padding: 10px 0;
}

/* 计时器区域（带暂停按钮）*/
#timerArea.timer-area-with-pause {
  display: flex !important;
  align-items: center;
  justify-content: center;
  gap: 10px;
}

/* 棋盘区域 */
.board-wrapper {
  display: flex;
  justify-content: center;
  margin: 5px 0 20px 0;
  position: relative;
}

#board {
  display: grid;
  grid-template-columns: repeat(9, var(--cell-size));
  grid-auto-rows: var(--cell-size);
  border: 2px solid var(--border-thick);
  background: var(--bg-board);
  box-shadow: var(--shadow-card);
}

.cell {
  width: var(--cell-size);
  height: var(--cell-size);
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border-normal);
  font-size: 20px;
  position: relative;
  color: var(--text-primary);
}

/* 加粗边框逻辑 */
.cell:nth-child(3n):not(:nth-child(9n)) { border-right: 2px solid var(--border-thick); }
/* 行加粗由JS控制或 nth-child 控制，这里为了简单保留JS逻辑或用CSS */
.cell:nth-child(n+19):nth-child(-n+27),
.cell:nth-child(n+46):nth-child(-n+54) {
    border-bottom: 2px solid var(--border-thick);
}
/* 为了修正JS里的 border-bottom 覆盖问题，CSS选择器优先级要处理好，或者保持JS添加样式 */

.prefilled {
  background: var(--bg-prefilled);
  font-weight: 600;
}

input.cell-input {
  width: 100%;
  height: 100%;
  border: 0;
  outline: 0;
  text-align: center;
  font-size: 20px;
  background: transparent;
  caret-color: var(--caret-color);
  color: var(--text-primary);
  padding: 0;
  margin: 0;
  line-height: 1;
  font-family: inherit;
  font-weight: normal;
}

.conflict {
  background: var(--conflict-bg) !important;
  color: var(--conflict-text) !important;
}
.conflict input { color: var(--conflict-text) !important; }

/* 记录区域 */
#records, .changelog-details {
  width: 100%;
  max-width: 100%; /* 撑满 main-container */
  padding: 16px;
  background: var(--bg-records);
  border: 1px solid var(--border-normal);
  border-radius: 8px;
  box-shadow: var(--shadow-card);
  font-size: 14px;
}

.record-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-normal);
}

.record-row {
  display: flex;
  justify-content: space-between;
  padding: 8px 0;
  border-bottom: 1px dashed var(--border-normal);
}
.record-row:last-child { border-bottom: 0; }

.changelog-details summary {
  font-weight: 600;
  cursor: pointer;
}

/* 响应式调整 */
@media (max-width: 600px) {
  .header-section { flex-direction: column; align-items: flex-start; }
  .login-area { width: 100%; justify-content: space-between; }
  .login-area .form-control { flex-grow: 1; width: auto; }

  .controls-bar { flex-wrap: wrap; }
  .controls-group { flex-grow: 1; }
  #difficulty { flex-grow: 1; }

  #board {
    grid-template-columns: repeat(9, var(--cell-size-mobile));
    grid-auto-rows: var(--cell-size-mobile);
  }
  .cell { width: var(--cell-size-mobile); height: var(--cell-size-mobile); font-size: 18px; }
  input.cell-input { font-size: 18px; }

  #language-selector {
    width: 80px;  /* 移动端可以更小 */
    min-width: 80px;
  }
  
  #language-selector option {
    font-size: 20px;  /* 增大emoji在移动端的显示 */
    padding: 10px;
  }
}

/* Toast 通知系统样式 */
.toast-container {
  position: fixed;
  top: 20px;
  right: 20px;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 10px;
  pointer-events: none;
}

.toast {
  min-width: 250px;
  max-width: 400px;
  padding: 12px 16px;
  background: var(--bg-board);
  border: 1px solid var(--border-normal);
  border-radius: 8px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  display: flex;
  align-items: center;
  gap: 10px;
  animation: slideIn 0.3s ease-out;
  pointer-events: auto;
}

@keyframes slideIn {
  from {
    transform: translateX(400px);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

@keyframes slideOut {
  from {
    transform: translateX(0);
    opacity: 1;
  }
  to {
    transform: translateX(400px);
    opacity: 0;
  }
}

.toast-success {
  border-left: 4px solid #22c55e;
}
.toast-error {
  border-left: 4px solid #ef4444;
}
.toast-warning {
  border-left: 4px solid #f59e0b;
}
.toast-info {
  border-left: 4px solid #3b82f6;
}

.toast-icon {
  font-size: 18px;
  flex-shrink: 0;
}
.toast-message {
  flex-grow: 1;
  color: var(--text-primary);
}
.toast-close {
  background: none;
  border: none;
  font-size: 20px;
  cursor: pointer;
  opacity: 0.5;
  color: var(--text-secondary);
  padding: 0;
  margin: 0;
  width: 20px;
  height: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}
.toast-close:hover {
  opacity: 1;
}

/* 响应式 Toast */
@media (max-width: 600px) {
  .toast-container {
    top: 10px;
    right: 10px;
    left: 10px;
  }
  .toast {
    min-width: auto;
    width: 100%;
  }
}

/* 语言选择器特定样式 */
#language-selector {
  width: 100px; /* 覆盖 .form-control 的 200px 默认宽度 */
  min-width: 100px;
}

/* 暂停遮罩样式 */
.pause-overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(13, 17, 23, 0.9);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  border-radius: 4px;
  animation: fadeIn 0.2s ease-out;
}

.pause-content {
  text-align: center;
  color: var(--text-primary);
}

.pause-icon {
  font-size: 48px;
  margin-bottom: 16px;
}

.pause-title {
  font-size: 24px;
  margin: 0 0 20px 0;
  font-weight: 700;
}

.btn-lg {
  height: 48px;
  padding: 0 24px;
  font-size: 16px;
}

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

/* 暂停按钮样式 */
.pause-btn {
  background: none;
  border: none;
  font-size: 20px;
  cursor: pointer;
  padding: 4px 8px;
  color: var(--text-primary);
  transition: transform 0.2s;
  border-radius: 4px;
}

.pause-btn:hover {
  transform: scale(1.1);
  background: var(--btn-hover);
}

/* 当暂停时，禁用棋盘交互 */
.board-wrapper:has(.pause-overlay[style*="display: flex"]) #board {
  pointer-events: none;
  filter: blur(2px);
}

/* 暗色模式下的暂停遮罩 */
@media (prefers-color-scheme: dark) {
  .pause-overlay {
    background: rgba(22, 27, 34, 0.95);
  }
}

/* 移动端响应式 */
@media (max-width: 600px) {
  .pause-icon {
    font-size: 36px;
  }

  .pause-title {
    font-size: 20px;
  }

  .btn-lg {
    height: 44px;
    font-size: 14px;
  }
}