/* ============================================
   数据结构课程网站 - 公共样式
   三端适配：PC / 平板 / 手机
   ============================================ */

:root {
  --bg: #f5f7fa;
  --bg2: #ffffff;
  --ink: #1a1a2e;
  --muted: #6c757d;
  --rule: #e2e8f0;
  --accent: #4361ee;
  --accent2: #3f37c9;
  --accent-light: #edf2ff;
  --success: #2a9d8f;
  --warn: #e9c46a;
  --danger: #e63946;
  --shadow: 0 2px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.12);
  --radius: 12px;
  --radius-sm: 8px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC',
               'Microsoft YaHei', 'Helvetica Neue', sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.6;
  font-size: 15px;
  min-height: 100vh;
}

/* 布局容器 */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* 顶部导航 */
.top-nav {
  background: var(--bg2);
  border-bottom: 1px solid var(--rule);
  padding: 12px 0;
  position: sticky;
  top: 0;
  z-index: 200;
  box-shadow: 0 1px 4px rgba(0,0,0,0.04);
}
.top-nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
}
.top-nav .site-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--accent);
  text-decoration: none;
}
.top-nav .nav-links {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.top-nav .nav-links a {
  font-size: 0.82rem;
  color: var(--muted);
  text-decoration: none;
  padding: 5px 12px;
  border-radius: var(--radius-sm);
  transition: all 0.2s;
  white-space: nowrap;
}
.top-nav .nav-links a:hover,
.top-nav .nav-links a.active {
  color: var(--accent);
  background: var(--accent-light);
}

/* 章节导航 */
.chapter-nav {
  background: var(--bg2);
  border-bottom: 1px solid var(--rule);
  padding: 10px 0;
  position: sticky;
  top: 50px;
  z-index: 150;
}
.chapter-nav-inner {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
}
.chapter-nav a {
  font-size: 0.8rem;
  color: var(--muted);
  text-decoration: none;
  padding: 4px 10px;
  border-radius: 20px;
  border: 1px solid var(--rule);
  transition: all 0.2s;
  white-space: nowrap;
}
.chapter-nav a:hover,
.chapter-nav a.active {
  color: var(--accent);
  border-color: var(--accent);
  background: var(--accent-light);
}

/* 页面标题区 */
.page-header {
  background: linear-gradient(135deg, var(--accent) 0%, var(--accent2) 100%);
  color: #fff;
  padding: 40px 0 32px;
  text-align: center;
}
.page-header h1 {
  font-size: 1.8rem;
  font-weight: 700;
  margin-bottom: 8px;
}
.page-header .subtitle {
  font-size: 0.95rem;
  opacity: 0.85;
}

/* 内容区 */
.page-content {
  padding: 30px 0 60px;
}

/* 卡片 */
.card {
  background: var(--bg2);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 20px;
  box-shadow: var(--shadow);
}
.card-title {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--ink);
  display: flex;
  align-items: center;
  gap: 10px;
}
.card-title .icon {
  width: 32px;
  height: 32px;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
}

/* 控制面板 */
.control-panel {
  background: #f8f9fa;
  border: 1px solid var(--rule);
  border-radius: var(--radius-sm);
  padding: 16px 20px;
  margin-bottom: 20px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: center;
}
.control-panel .ctrl-group {
  display: flex;
  align-items: center;
  gap: 8px;
}
.control-panel label {
  font-size: 0.85rem;
  color: var(--muted);
  white-space: nowrap;
}

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 18px;
  font-size: 0.88rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.2s;
  white-space: nowrap;
}
.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}
.btn-primary {
  background: var(--accent);
  color: #fff;
}
.btn-primary:hover:not(:disabled) {
  background: var(--accent2);
  transform: translateY(-1px);
}
.btn-secondary {
  background: var(--bg);
  color: var(--ink);
  border: 1px solid var(--rule);
}
.btn-secondary:hover:not(:disabled) {
  background: var(--rule);
}
.btn-success {
  background: var(--success);
  color: #fff;
}
.btn-danger {
  background: var(--danger);
  color: #fff;
}
.btn-sm {
  padding: 5px 12px;
  font-size: 0.8rem;
}

/* 输入框 */
input[type="text"],
input[type="number"],
select,
textarea {
  padding: 8px 12px;
  border: 1px solid var(--rule);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-family: inherit;
  background: var(--bg2);
  color: var(--ink);
  transition: border-color 0.2s;
}
input[type="text"]:focus,
input[type="number"]:focus,
select:focus,
textarea:focus {
  outline: none;
  border-color: var(--accent);
}

/* 滑块 */
input[type="range"] {
  width: 120px;
  cursor: pointer;
}

/* 可视化区域 */
.viz-container {
  background: #fafbfc;
  border: 1px solid var(--rule);
  border-radius: var(--radius-sm);
  padding: 20px;
  min-height: 300px;
  position: relative;
  overflow: auto;
}
.viz-container canvas {
  display: block;
  margin: 0 auto;
  max-width: 100%;
}

/* 状态信息 */
.status-bar {
  background: var(--accent-light);
  border-left: 3px solid var(--accent);
  padding: 10px 16px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-size: 0.88rem;
  color: var(--accent2);
  margin-bottom: 16px;
}

/* 代码块 */
.code-block {
  background: #1e1e2e;
  color: #cdd6f4;
  padding: 16px 20px;
  border-radius: var(--radius-sm);
  font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
  font-size: 0.85rem;
  line-height: 1.6;
  overflow-x: auto;
  margin: 12px 0;
}
.code-block .comment { color: #6c7086; }
.code-block .keyword { color: #cba6f7; }
.code-block .string { color: #a6e3a1; }
.code-block .number { color: #fab387; }

/* 表格 */
.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  margin: 12px 0;
}
.data-table th,
.data-table td {
  padding: 10px 14px;
  text-align: center;
  border: 1px solid var(--rule);
}
.data-table th {
  background: var(--accent-light);
  color: var(--accent2);
  font-weight: 600;
}
.data-table tr:nth-child(even) {
  background: #f8f9fa;
}

/* 标签 */
.tag {
  display: inline-block;
  font-size: 0.75rem;
  padding: 2px 10px;
  border-radius: 20px;
  font-weight: 600;
}
.tag-blue { background: var(--accent-light); color: var(--accent2); }
.tag-green { background: #e6fcf5; color: #087f5b; }
.tag-orange { background: #fff9db; color: #b45309; }
.tag-red { background: #fff5f5; color: #c92a2a; }

/* 步骤指示器 */
.step-indicator {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}
.step-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--rule);
  transition: background 0.3s;
}
.step-dot.active { background: var(--accent); }
.step-dot.done { background: var(--success); }

/* 进度条 */
.progress-bar {
  width: 100%;
  height: 6px;
  background: var(--rule);
  border-radius: 3px;
  overflow: hidden;
  margin: 8px 0;
}
.progress-bar .progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent2));
  border-radius: 3px;
  transition: width 0.3s;
}

/* 提示框 */
.tooltip {
  position: relative;
}
.tooltip::after {
  content: attr(data-tip);
  position: absolute;
  bottom: 100%;
  left: 50%;
  transform: translateX(-50%);
  background: var(--ink);
  color: #fff;
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 0.78rem;
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s;
  z-index: 100;
}
.tooltip:hover::after {
  opacity: 1;
}

/* 响应式 */
@media (max-width: 768px) {
  body { font-size: 14px; }
  .container { padding: 0 14px; }
  .page-header h1 { font-size: 1.4rem; }
  .page-header { padding: 28px 0 22px; }
  .card { padding: 16px; }
  .control-panel { padding: 12px 14px; }
  .btn { padding: 7px 14px; font-size: 0.85rem; }
  .top-nav .nav-links { gap: 4px; }
  .top-nav .nav-links a { padding: 4px 8px; font-size: 0.78rem; }
  .viz-container { padding: 12px; min-height: 220px; }
}

@media (max-width: 480px) {
  .page-header h1 { font-size: 1.2rem; }
  .card-title { font-size: 1rem; }
  .control-panel { flex-direction: column; align-items: stretch; }
  .control-panel .ctrl-group { justify-content: space-between; }
  input[type="range"] { width: 100px; }
}

/* 动画 */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}
.fade-in {
  animation: fadeIn 0.4s ease-out;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.5; }
}
.pulse {
  animation: pulse 1.5s infinite;
}

/* 隐藏滚动条但保持功能 */
.hide-scrollbar {
  scrollbar-width: none;
  -ms-overflow-style: none;
}
.hide-scrollbar::-webkit-scrollbar {
  display: none;
}