:root {
    --bg: #f5f7fa;
    --bg-card: #ffffff;
    --text: #1a1a2e;
    --text-secondary: #555;
    --primary: #e94560;
    --primary-dark: #c23152;
    --border: #e0e0e0;
    --shadow: 0 8px 30px rgba(0,0,0,0.08);
    --radius: 16px;
    --transition: all 0.3s ease;
    --font: 'Segoe UI', system-ui, -apple-system, sans-serif;
}
[data-theme="tech"] {
    --bg: #0a0a23;
    --bg-card: #1a1a3e;
    --text: #e0e0ff;
    --primary: #00d4ff;
    --primary-dark: #0099cc;
}
[data-theme="fashion"] {
    --bg: #fff5f7;
    --bg-card: #ffffff;
    --text: #2d1b2e;
    --primary: #e84393;
    --primary-dark: #c2316a;
}
[data-theme="food"] {
    --bg: #fff8f0;
    --bg-card: #ffffff;
    --text: #3e2723;
    --primary: #ff6f00;
    --primary-dark: #e65100;
}
body.dark-mode {
    --bg: #121212;
    --bg-card: #1e1e2f;
    --text: #e0e0e0;
    --text-secondary: #aaa;
    --border: #333;
    --shadow: 0 8px 30px rgba(0,0,0,0.5);
}
* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: var(--font); background: var(--bg); color: var(--text); line-height: 1.6; transition: var(--transition); }
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }
a { color: var(--primary); text-decoration: none; }
img { max-width: 100%; }
.btn { display: inline-block; padding: 12px 28px; border-radius: 30px; border: none; font-weight: 600; cursor: pointer; transition: var(--transition); font-size: 1rem; }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); transform: translateY(-2px); box-shadow: 0 6px 20px rgba(233,69,96,0.3); }
.btn-outline { background: transparent; border: 2px solid var(--primary); color: var(--primary); }
.btn-outline:hover { background: var(--primary); color: #fff; }
.btn-sm { padding: 8px 20px; font-size: 0.9rem; }
.icon-btn { background: none; border: none; font-size: 1.4rem; color: var(--text); cursor: pointer; padding: 8px; border-radius: 50%; transition: var(--transition); }
.icon-btn:hover { background: rgba(0,0,0,0.05); }
.hidden { display: none; }
.section-title { text-align: center; font-size: 2rem; margin-bottom: 2.5rem; position: relative; }
.section-title::after { content: ''; display: block; width: 60px; height: 4px; background: var(--primary); margin: 10px auto 0; border-radius: 2px; }

/* 导航 */
.navbar { background: var(--bg-card); box-shadow: 0 2px 10px rgba(0,0,0,0.05); position: sticky; top: 0; z-index: 1000; }
.navbar .container { display: flex; align-items: center; justify-content: space-between; height: 70px; }
.logo { font-size: 1.8rem; font-weight: 800; color: var(--primary); }
.nav-links a { margin: 0 12px; font-weight: 500; color: var(--text); transition: var(--transition); }
.nav-links a:hover { color: var(--primary); }
.nav-actions { display: flex; align-items: center; gap: 10px; }
.hamburger { display: none; background: none; border: none; font-size: 1.6rem; color: var(--text); cursor: pointer; padding: 8px; }
@media (max-width: 768px) {
    .nav-links { display: none; flex-direction: column; background: var(--bg-card); position: absolute; top: 70px; left: 0; right: 0; padding: 20px; box-shadow: 0 10px 20px rgba(0,0,0,0.1); }
    .nav-links.active { display: flex; }
    .nav-links a { margin: 10px 0; }
    .hamburger { display: block; }
}

/* 搜索栏 */
.search-bar { background: var(--bg-card); padding: 15px 0; border-top: 1px solid var(--border); transition: var(--transition); }
.search-bar .container { display: flex; flex-wrap: wrap; gap: 10px; align-items: center; }
.search-bar input, .search-bar select { padding: 10px 15px; border-radius: 30px; border: 1px solid var(--border); background: var(--bg); color: var(--text); font-size: 0.95rem; flex: 1 1 150px; }
.search-bar .btn { flex: 0 0 auto; }

/* Hero */
.hero { background: linear-gradient(135deg, var(--primary) 0%, #0f3460 100%); color: #fff; padding: 100px 0; text-align: center; }
.hero h1 { font-size: 3rem; margin-bottom: 20px; }
.hero p { font-size: 1.2rem; margin-bottom: 30px; opacity: 0.9; }
.hero-buttons .btn { margin: 0 10px; }

/* 特色 */
.features { padding: 80px 0; }
.feature-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 30px; }
.feature-card { background: var(--bg-card); padding: 30px; border-radius: var(--radius); box-shadow: var(--shadow); text-align: center; transition: var(--transition); }
.feature-card:hover { transform: translateY(-5px); }
.feature-card i { font-size: 2.5rem; color: var(--primary); margin-bottom: 15px; }
.feature-card h3 { margin-bottom: 10px; }
.feature-card p { color: var(--text-secondary); }

/* 课程 */
.classes-section { padding: 80px 0; }
.class-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 25px; }
.class-card { background: var(--bg-card); border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow); transition: var(--transition); }
.class-card:hover { transform: translateY(-6px); }
.class-img { height: 140px; display: flex; align-items: center; justify-content: center; color: #fff; font-size: 3rem; }
.class-info { padding: 20px; }
.class-info h3 { margin-bottom: 8px; }
.class-meta { display: flex; gap: 15px; font-size: 0.9rem; color: var(--text-secondary); margin-bottom: 8px; }
.class-desc { font-size: 0.95rem; color: var(--text-secondary); margin-bottom: 10px; }
.class-price { font-weight: 700; color: var(--primary); margin-bottom: 10px; }
.class-tags { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 12px; }
.tag { background: var(--primary); color: #fff; padding: 3px 12px; border-radius: 20px; font-size: 0.75rem; }
.book-btn { width: 100%; }

/* 评价 */
.testimonials { padding: 80px 0; background: var(--bg-card); }
.testimonial-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 30px; }
.testimonial-card { background: var(--bg); padding: 25px; border-radius: var(--radius); box-shadow: var(--shadow); }
.stars i { color: #f5c518; margin-right: 2px; }
.testimonial-card p { font-style: italic; margin: 15px 0; }
.testimonial-author { display: flex; align-items: center; gap: 12px; }
.testimonial-author img { border-radius: 50%; width: 40px; height: 40px; object-fit: cover; }

/* 数据统计 */
.stats-heatmap { padding: 80px 0; }
.stats-bar { display: flex; justify-content: center; gap: 40px; margin-bottom: 30px; flex-wrap: wrap; }
.stat-item { font-size: 1.2rem; font-weight: 600; }
.stat-item i { color: var(--primary); margin-right: 8px; }
.heatmap-container { background: var(--bg-card); border-radius: var(--radius); padding: 20px; min-height: 120px; box-shadow: var(--shadow); display: flex; align-items: flex-end; gap: 6px; flex-wrap: wrap; justify-content: center; }
.heatmap-bar { width: 30px; background: var(--primary); border-radius: 6px 6px 0 0; transition: height 0.5s; min-height: 4px; opacity: 0.7; }
.heatmap-bar:hover { opacity: 1; }

/* 主题切换 */
.theme-switcher { padding: 60px 0; text-align: center; }
.theme-buttons { display: flex; justify-content: center; gap: 15px; flex-wrap: wrap; }
.theme-btn { padding: 12px 24px; border-radius: 30px; border: 2px solid var(--border); background: var(--bg-card); color: var(--text); cursor: pointer; font-size: 1rem; transition: var(--transition); }
.theme-btn:hover { border-color: var(--primary); color: var(--primary); }

/* 页脚 */
.footer { background: var(--bg-card); padding: 40px 0; text-align: center; border-top: 1px solid var(--border); }
.footer-links { margin-bottom: 15px; }
.footer-links a { margin: 0 12px; color: var(--text-secondary); }
.footer-links a:hover { color: var(--primary); }
.social-share { margin-bottom: 15px; }
.social-share a { margin: 0 10px; font-size: 1.5rem; color: var(--text-secondary); transition: var(--transition); }
.social-share a:hover { color: var(--primary); }
.footer p { color: var(--text-secondary); }

/* 内页通用 */
.page-hero { background: linear-gradient(135deg, var(--primary), #0f3460); color: #fff; padding: 60px 0; text-align: center; margin-bottom: 40px; }
.page-hero h1 { font-size: 2.5rem; }
.page-content { padding: 0 0 60px; }
.page-content .grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 25px; }

/* 管理后台登录 */
.admin-login-body { display: flex; justify-content: center; align-items: center; min-height: 100vh; background: var(--bg); }
.admin-login-box { background: var(--bg-card); padding: 40px; border-radius: var(--radius); box-shadow: var(--shadow); width: 360px; }
.admin-login-box h2 { margin-bottom: 20px; text-align: center; }
.admin-login-box input { width: 100%; padding: 12px; margin-bottom: 15px; border-radius: 8px; border: 1px solid var(--border); background: var(--bg); color: var(--text); }
.admin-login-box .error { color: red; margin-bottom: 10px; }
.admin-login-box .btn { width: 100%; }

/* 响应式 */
@media (max-width: 600px) {
    .hero h1 { font-size: 2rem; }
    .hero p { font-size: 1rem; }
    .search-bar .container { flex-direction: column; }
    .search-bar input, .search-bar select { width: 100%; }
    .stats-bar { gap: 20px; }
}