/* ========================================
   基础重置与全局变量
   ======================================== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --board-color: #DEB887;       /* 棋盘原木色 */
  --board-line: #8B6914;        /* 棋盘线颜色 */
  --primary: #4A90D9;           /* 主色调 */
  --primary-hover: #357ABD;
  --secondary: #95A5A6;
  --secondary-hover: #7F8C8D;
  --danger: #E74C3C;
  --bg: #1a1a2e;                /* 深色背景 */
  --panel-bg: #16213e;          /* 面板背景 */
  --panel-border: #0f3460;
  --text-primary: #e0e0e0;
  --text-secondary: #a0a0b0;
  --shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
  --radius: 12px;
}

body {
  font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
  background: var(--bg);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ========================================
   整体容器
   ======================================== */
.app-wrapper {
  width: 100%;
  max-width: 960px;
  padding: 20px;
}

/* ========================================
   顶部标题
   ======================================== */
.app-header {
  text-align: center;
  margin-bottom: 24px;
}

.app-header h1 {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: 4px;
  background: linear-gradient(135deg, #f5c518, #e0a800);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  text-shadow: none;
}

/* ========================================
   游戏主区域
   ======================================== */
.game-container {
  display: flex;
  gap: 24px;
  align-items: flex-start;
  justify-content: center;
}

/* ========================================
   棋盘区域
   ======================================== */
.board-wrapper {
  flex-shrink: 0;
  background: var(--board-color);
  border-radius: var(--radius);
  box-shadow: var(--shadow), inset 0 0 40px rgba(0,0,0,0.15);
  overflow: hidden;
  cursor: crosshair;
  transition: box-shadow 0.2s;
}

.board-wrapper:hover {
  box-shadow: 0 6px 30px rgba(0,0,0,0.5), inset 0 0 40px rgba(0,0,0,0.15);
}

#gomokuCanvas {
  display: block;
}

/* ========================================
   控制面板
   ======================================== */
.control-panel {
  flex: 1;
  min-width: 200px;
  max-width: 240px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.panel-section {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  padding: 16px;
}

.section-title {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 2px;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

/* 当前回合 */
.turn-indicator {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1rem;
  font-weight: 600;
}

.stone-icon {
  width: 24px;
  height: 24px;
  border-radius: 50%;
  display: inline-block;
  flex-shrink: 0;
}

.black-stone {
  background: radial-gradient(circle at 35% 35%, #4a4a4a, #0a0a0a);
  box-shadow: 2px 2px 6px rgba(0,0,0,0.5);
}

.white-stone {
  background: radial-gradient(circle at 35% 35%, #ffffff, #cccccc);
  box-shadow: 2px 2px 6px rgba(0,0,0,0.3);
  border: 1px solid #ddd;
}

/* 步数 */
.step-count {
  font-size: 2rem;
  font-weight: 700;
  color: var(--primary);
  text-align: center;
}

/* ========================================
   模式切换按钮
   ======================================== */
.mode-buttons {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.mode-btn {
  width: 100%;
  padding: 8px 12px;
  border: 1px solid var(--panel-border);
  border-radius: 6px;
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s;
}

.mode-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.mode-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
  font-weight: 600;
}

/* ========================================
   操作按钮
   ======================================== */
.actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.action-btn {
  width: 100%;
  padding: 10px 16px;
  border: none;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  letter-spacing: 1px;
}

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

.action-btn.primary:hover {
  background: var(--primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(74, 144, 217, 0.4);
}

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

.action-btn.secondary:hover {
  background: var(--secondary-hover);
  transform: translateY(-1px);
}

.action-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none !important;
  box-shadow: none !important;
}

/* ========================================
   规则说明
   ======================================== */
.rules ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.rules ul li {
  font-size: 0.8rem;
  color: var(--text-secondary);
  padding-left: 14px;
  position: relative;
}

.rules ul li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--primary);
}

/* ========================================
   胜利弹窗
   ======================================== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.7);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s;
  backdrop-filter: blur(4px);
}

.modal-overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

.modal {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: 20px;
  padding: 40px 48px;
  text-align: center;
  box-shadow: 0 20px 60px rgba(0,0,0,0.6);
  transform: scale(0.85);
  transition: transform 0.3s;
}

.modal-overlay.visible .modal {
  transform: scale(1);
}

.modal-icon {
  font-size: 3.5rem;
  margin-bottom: 12px;
}

.modal-title {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: #f5c518;
}

.modal-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

/* ========================================
   难度选择器样式
   ======================================== */
.difficulty-select {
  width: 100%;
  padding: 10px 12px;
  border: 1px solid var(--panel-border);
  border-radius: 8px;
  background: var(--panel-bg);
  color: var(--text-primary);
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.2s;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23a0a0b0' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 12px center;
  padding-right: 36px;
}

.difficulty-select:hover {
  border-color: var(--primary);
}

.difficulty-select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(74, 144, 217, 0.2);
}

.difficulty-select option {
  background: var(--panel-bg);
  color: var(--text-primary);
  padding: 8px;
}

/* ========================================
   响应式适配
   ======================================== */
@media (max-width: 720px) {
  body {
    align-items: flex-start;
    padding-top: 10px;
  }

  .app-wrapper {
    padding: 10px;
  }

  .app-header {
    margin-bottom: 12px;
  }

  .app-header h1 {
    font-size: 1.5rem;
  }

  .game-container {
    flex-direction: column;
    align-items: center;
    gap: 16px;
  }

  .board-wrapper {
    width: calc(100vw - 20px);
    max-width: 500px;
  }

  #gomokuCanvas {
    width: 100%;
    height: auto;
  }

  .control-panel {
    max-width: 100%;
    width: 100%;
    flex-direction: row;
    flex-wrap: wrap;
    gap: 8px;
  }

  .panel-section {
    flex: 1 1 45%;
    padding: 12px;
  }

  .current-turn {
    flex: 1 1 100%;
  }

  .turn-indicator {
    justify-content: center;
  }

  .turn-text {
    font-size: 1.2rem;
  }

  .step-count {
    font-size: 1.5rem;
  }

  .actions {
    flex-direction: row;
    flex: 1 1 100%;
  }

  .actions .action-btn {
    flex: 1;
  }

  .rules {
    flex: 1 1 100%;
  }

  .difficulty-section {
    flex: 1 1 100%;
  }

  .modal {
    width: calc(100vw - 40px);
    padding: 24px;
  }

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

  .modal-icon {
    font-size: 2.5rem;
  }
}

@media (max-width: 400px) {
  .panel-section {
    flex: 1 1 100%;
  }

  .mode-buttons {
    flex-direction: row;
  }

  .mode-btn {
    flex: 1;
  }
}