/* ==================== CSS 变量与全局样式 ==================== */
:root {
  --bg: #f8fafc;
  --surface: #ffffff;
  --border: #e2e8f0;
  --text: #1e293b;
  --text-secondary: #64748b;
  --primary: #3b82f6;
  --primary-light: #eff6ff;
  --primary-dark: #2563eb;
  --accent: #06b6d4;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.07), 0 2px 4px rgba(0,0,0,0.06);
  --radius: 8px;
  --transition: 0.2s ease;
  --sidebar-width: 260px;
  --navbar-height: 56px;
}

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

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

a { color: var(--primary); text-decoration: none; }
a:hover { color: var(--primary-dark); }

/* ==================== 顶部导航栏 ==================== */
.navbar {
  position: fixed; top: 0; left: 0; right: 0; z-index: 110;
  height: var(--navbar-height);
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 20px;
}
.navbar .logo {
  font-size: 18px; font-weight: 700; color: var(--primary);
  display: flex; align-items: center; gap: 8px;
}
.navbar .logo span { font-size: 22px; }
.navbar .logo a { color: var(--primary); display: flex; align-items: center; gap: 8px; }
.nav-links { display: flex; gap: 4px; list-style: none; }
.nav-links li a {
  display: block; padding: 8px 16px; border-radius: var(--radius);
  color: var(--text-secondary); font-size: 14px; font-weight: 500;
  transition: all var(--transition);
}
.nav-links li a:hover,
.nav-links li a.active { background: var(--primary-light); color: var(--primary); }
.menu-toggle {
  display: none; background: none; border: none; font-size: 24px;
  cursor: pointer; color: var(--text); padding: 4px 8px;
}

/* ==================== 布局 ==================== */
.page-wrapper { display: flex; padding-top: var(--navbar-height); min-height: 100vh; }

/* ==================== 侧边栏 ==================== */
.sidebar {
  width: var(--sidebar-width); min-width: var(--sidebar-width);
  background: var(--surface); border-right: 1px solid var(--border);
  position: fixed; top: var(--navbar-height); bottom: 0; left: 0;
  overflow-y: auto; padding: 16px 0; z-index: 90;
  transition: transform var(--transition);
}
.sidebar-title {
  font-size: 14px; font-weight: 600; color: var(--text-secondary);
  padding: 0 16px 8px; text-transform: uppercase; letter-spacing: 0.5px;
}
.sidebar .course-group { margin-bottom: 4px; }
.sidebar .course-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 10px 16px; cursor: pointer; font-size: 14px; font-weight: 500;
  color: var(--text); transition: background var(--transition);
}
.sidebar .course-header:hover { background: var(--primary-light); }
.sidebar .course-header .arrow { font-size: 10px; transition: transform var(--transition); }
.sidebar .course-header.open .arrow { transform: rotate(90deg); }
.sidebar .chapter-list { display: none; }
.sidebar .chapter-list.open { display: block; }
.sidebar .chapter-list a {
  display: block; padding: 6px 16px 6px 36px; font-size: 13px;
  color: var(--text-secondary); transition: all var(--transition);
  border-left: 2px solid transparent;
}
.sidebar .chapter-list a:hover,
.sidebar .chapter-list a.active {
  color: var(--primary); background: var(--primary-light);
  border-left-color: var(--primary);
}
.sidebar-overlay { display: none; }

/* ==================== 主内容区 ==================== */
.main-content {
  margin-left: var(--sidebar-width);
  flex: 1; padding: 24px;
  max-width: 1000px; width: 100%;
}

/* ==================== 卡片样式 ==================== */
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px; margin-bottom: 20px;
  box-shadow: var(--shadow-sm);
}
.card h2 { font-size: 20px; margin-bottom: 12px; color: var(--text); }
.card h3 { font-size: 16px; margin: 16px 0 8px; color: var(--text); }
.card p { color: var(--text-secondary); font-size: 14px; margin-bottom: 8px; }

/* 标签 */
.tag {
  display: inline-block; padding: 2px 10px; border-radius: 12px;
  font-size: 12px; font-weight: 500;
}
.tag-blue { background: #dbeafe; color: #1e40af; }
.tag-green { background: #d1fae5; color: #065f46; }
.tag-yellow { background: #fef3c7; color: #92400e; }
.tag-red { background: #fee2e2; color: #991b1b; }

/* 进度条 */
.progress-bar {
  height: 8px; background: #e2e8f0; border-radius: 4px; overflow: hidden; margin: 8px 0;
}
.progress-bar .fill {
  height: 100%; background: var(--primary); border-radius: 4px;
  transition: width 0.5s ease;
}
.progress-label {
  display: flex; justify-content: space-between; font-size: 13px; color: var(--text-secondary);
}

/* ==================== 课程网格 ==================== */
.course-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 16px; }
.course-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 20px; cursor: pointer;
  transition: all var(--transition); box-shadow: var(--shadow-sm);
  display: block; color: var(--text);
}
.course-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); color: var(--text); }
.course-card .icon { font-size: 32px; margin-bottom: 8px; }
.course-card h4 { font-size: 16px; margin-bottom: 6px; }
.course-card p { font-size: 13px; color: var(--text-secondary); }

/* ==================== 知识点面板 ==================== */
.knowledge-block {
  background: var(--primary-light); border: 1px solid #bfdbfe;
  border-radius: var(--radius); padding: 16px; margin: 12px 0;
}
.knowledge-block h4 { font-size: 15px; color: var(--primary-dark); margin-bottom: 6px; }
.knowledge-block ul { padding-left: 20px; }
.knowledge-block li { font-size: 13px; color: var(--text-secondary); margin: 4px 0; }

.summary-box {
  background: #fefce8; border: 1px solid #fde68a;
  border-radius: var(--radius); padding: 14px; margin: 12px 0;
}
.summary-box h4 { font-size: 14px; color: #a16207; margin-bottom: 4px; }

/* ==================== 按钮 ==================== */
.btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 8px 16px; border-radius: var(--radius); font-size: 14px;
  font-weight: 500; border: 1px solid transparent; cursor: pointer;
  transition: all var(--transition); text-decoration: none;
}
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); color: #fff; }
.btn-outline { background: var(--surface); border-color: var(--border); color: var(--text); }
.btn-outline:hover { border-color: var(--primary); color: var(--primary); }
.btn-success { background: var(--success); color: #fff; }
.btn-success:hover { opacity: 0.9; color: #fff; }
.btn-danger { background: var(--danger); color: #fff; }
.btn-danger:hover { opacity: 0.9; color: #fff; }
.btn-sm { padding: 4px 10px; font-size: 12px; }

/* ==================== 代码编辑器 ==================== */
.code-editor-wrap {
  border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden;
}
.code-editor-wrap textarea {
  width: 100%; height: 200px; padding: 14px;
  font-family: 'Cascadia Code', 'Fira Code', 'Consolas', monospace;
  font-size: 13px; line-height: 1.6; background: #1e293b; color: #e2e8f0;
  border: none; outline: none; resize: vertical; tab-size: 4;
}
.code-output {
  background: #0f172a; color: #94a3b8; padding: 12px 14px;
  font-family: 'Consolas', monospace; font-size: 13px;
  min-height: 40px; max-height: 150px; overflow-y: auto;
  white-space: pre-wrap;
}
.code-toolbar {
  display: flex; gap: 8px; padding: 10px; background: #f1f5f9;
  border-top: 1px solid var(--border);
}
/* 学习页代码展示——自动撑开完整显示 */
.code-editor-wrap textarea.code-display {
  height: auto; min-height: 60px; max-height: 600px;
  overflow-y: auto; resize: none; cursor: default;
  background: #1e293b; color: #e2e8f0; padding: 14px;
  font-family: 'Consolas', 'Fira Code', monospace;
  font-size: 13px; line-height: 1.6;
  width: 100%; border: none; outline: none;
}

/* ==================== 题目样式 ==================== */
.quiz-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 20px; margin-bottom: 16px;
}
.quiz-card .q-header {
  display: flex; justify-content: space-between; align-items: center; margin-bottom: 10px;
}
.quiz-card .q-num { font-weight: 600; font-size: 15px; }
.quiz-card .q-type { font-size: 12px; }
.quiz-card .q-text { font-size: 14px; margin-bottom: 12px; }
.quiz-card .option {
  display: block; padding: 10px 14px; margin: 4px 0; border: 1px solid var(--border);
  border-radius: var(--radius); cursor: pointer; font-size: 14px;
  transition: all var(--transition);
}
.quiz-card .option:hover { background: var(--primary-light); border-color: var(--primary); }
.quiz-card .option.selected { background: var(--primary-light); border-color: var(--primary); }
.quiz-card .option.correct { background: #d1fae5; border-color: var(--success); }
.quiz-card .option.wrong { background: #fee2e2; border-color: var(--danger); }
.quiz-card input[type="text"] {
  width: 100%; padding: 10px; border: 1px solid var(--border);
  border-radius: var(--radius); font-size: 14px; margin: 8px 0;
}
.quiz-card .explain {
  display: none; margin-top: 10px; padding: 10px;
  background: #f0fdf4; border-radius: var(--radius);
}

/* ==================== 考试样式 ==================== */
.exam-header { text-align: center; padding: 30px; }
.exam-header .timer { font-size: 36px; font-weight: 700; color: var(--primary); }
.exam-nav { display: flex; justify-content: space-between; align-items: center; margin: 12px 0; }
.exam-nav .q-indicator { font-size: 14px; color: var(--text-secondary); }
.score-card { text-align: center; padding: 30px; }
.score-card .score { font-size: 64px; font-weight: 700; color: var(--primary); }

/* ==================== 笔记区 ==================== */
.notes-area textarea {
  width: 100%; height: 250px; padding: 14px; border: 1px solid var(--border);
  border-radius: var(--radius); font-size: 14px; font-family: inherit;
  resize: vertical; line-height: 1.6;
}

/* ==================== 表格 ==================== */
.data-table {
  width: 100%; border-collapse: collapse; font-size: 14px;
}
.data-table th, .data-table td {
  padding: 10px 14px; text-align: left; border-bottom: 1px solid var(--border);
}
.data-table th { background: #f8fafc; font-weight: 600; color: var(--text-secondary); }

/* ==================== 面包屑 ==================== */
.breadcrumb { font-size: 13px; color: var(--text-secondary); margin-bottom: 12px; }
.breadcrumb a { color: var(--text-secondary); }
.breadcrumb a:hover { color: var(--primary); }
.breadcrumb span { margin: 0 6px; }

/* ==================== 响应式设计 ==================== */
@media (max-width: 768px) {
  .menu-toggle { display: block; }
  .nav-links {
    display: none; position: absolute; top: var(--navbar-height); left: 0; right: 0;
    background: var(--surface); flex-direction: column; padding: 8px;
    border-bottom: 1px solid var(--border); box-shadow: var(--shadow-md);
  }
  .nav-links.open { display: flex; }
  /* 移动端导航链接触控优化（至少44px） */
  .nav-links li a { padding: 12px 16px; font-size: 15px; min-height: 44px; }

  .sidebar {
    transform: translateX(-100%); z-index: 99;
  }
  .sidebar.mobile-open { transform: translateX(0); }
  .sidebar-overlay {
    display: none; position: fixed; inset: 0; top: var(--navbar-height);
    background: rgba(0,0,0,0.3); z-index: 98;
  }
  .sidebar-overlay.show { display: block; }

  .main-content { margin-left: 0; padding: 16px; }
  .course-grid { grid-template-columns: 1fr; }

  /* 移动端按钮触控优化 */
  .btn { min-height: 44px; padding: 10px 16px; font-size: 14px; }
  .btn-sm { min-height: 36px; padding: 6px 12px; }
  .course-card { padding: 16px; }
  .quiz-card .option { padding: 12px 14px; min-height: 44px; }
}

/* 移动端浮动目录按钮 */
#mobileSidebarBtn {
  position: fixed; bottom: 20px; right: 20px; z-index: 200;
  padding: 10px 16px; background: var(--primary); color: #fff;
  border: none; border-radius: 20px; font-size: 14px;
  cursor: pointer; box-shadow: var(--shadow-md); display: none;
}
@media (max-width: 768px) {
  #mobileSidebarBtn { display: block; }
}

/* ==================== 专业报告卡片 ==================== */
.report-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 16px; }
.report-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 20px;
  box-shadow: var(--shadow-sm); transition: all var(--transition);
}
.report-card:hover { box-shadow: var(--shadow-md); transform: translateY(-2px); }
.report-header { display: flex; align-items: center; gap: 12px; }
.report-icon {
  width: 48px; height: 48px; background: var(--primary-light);
  border-radius: 12px; display: flex; align-items: center;
  justify-content: center; font-size: 24px; flex-shrink: 0;
}
.report-card h4 { font-size: 15px; margin: 0; color: var(--text); }
.report-stats {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(90px, 1fr));
  gap: 8px; margin: 10px 0; padding: 10px;
  background: var(--bg); border-radius: 6px;
}
.report-stat-item { text-align: center; }
.stat-value { display: block; font-size: 16px; font-weight: 700; color: var(--primary); }
.stat-label { display: block; font-size: 10px; color: var(--text-secondary); margin-top: 2px; }
.mini-table {
  width: 100%; font-size: 11px; border-collapse: collapse; margin: 6px 0;
}
.mini-table th, .mini-table td {
  padding: 4px 8px; text-align: left; border-bottom: 1px solid var(--border);
}
.mini-table th { background: #f8fafc; font-weight: 600; color: var(--text-secondary); }

/* ==================== 返回顶部按钮 ==================== */
#backToTop {
  position: fixed; bottom: 80px; right: 20px; z-index: 200;
  width: 40px; height: 40px; background: var(--primary); color: #fff;
  border: none; border-radius: 50%; font-size: 20px; cursor: pointer;
  box-shadow: var(--shadow-md); opacity: 0; transform: translateY(20px);
  transition: all 0.3s ease; pointer-events: none;
}
#backToTop.show { opacity: 1; transform: translateY(0); pointer-events: auto; }
#backToTop:hover { background: var(--primary-dark); transform: scale(1.1); }

/* ==================== 复制代码按钮 ==================== */
.copy-code-btn {
  position: absolute; top: 8px; right: 8px;
  padding: 4px 10px; background: rgba(255,255,255,0.15); color: #e2e8f0;
  border: 1px solid rgba(255,255,255,0.2); border-radius: 4px;
  font-size: 11px; cursor: pointer; transition: all 0.2s;
}
.copy-code-btn:hover { background: rgba(255,255,255,0.25); }

.code-editor-wrap { position: relative; }

/* ==================== 补充动画 ==================== */
.course-card { animation: fadeIn 0.4s ease both; }
.course-card:nth-child(2) { animation-delay: 0.1s; }
.course-card:nth-child(3) { animation-delay: 0.2s; }
.course-card:nth-child(4) { animation-delay: 0.3s; }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }