* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', 'Microsoft YaHei', sans-serif;
        }
        
        :root {
            --primary: #2563EB; /* 教育蓝主色调 */
            --accent: #F59E0B;  /* 活力橙色强调色 */
            --secondary: #10B981; /* 成功绿色 */
            --light-bg: #F8FAFC; /* 浅灰色背景 */
            --dark-text: #1E293B; /* 深色文字 */
            --medium-text: #64748B; /* 中等灰色文字 */
            --white: #FFFFFF;
            --border-radius: 8px;
            --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
            --transition: all 0.3s ease;
        }
        
        body {
            color: var(--dark-text);
            line-height: 1.6;
            background-color: var(--white);
        }
        
        .container {
            width: 100%;
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
        }
        
        /* 导航栏样式 */
        header {
            background-color: var(--white);
            box-shadow: var(--shadow);
            position: sticky;
            top: 0;
            z-index: 1000;
        }
        
        .navbar {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 15px 0;
        }
        
        .logo {
            display: flex;
            align-items: center;
            font-size: 24px;
            font-weight: 700;
            color: var(--primary);
        }
        
        .logo i {
            margin-right: 10px;
            color: var(--accent);
        }
        
        .nav-links {
            display: flex;
            list-style: none;
        }
        
        .nav-links li {
            margin-left: 30px;
        }
        
        .nav-links a {
            text-decoration: none;
            color: var(--dark-text);
            font-weight: 500;
            transition: var(--transition);
            padding: 5px 0;
            position: relative;
        }
        
        .nav-links a:hover {
            color: var(--primary);
        }
        
        .nav-links a::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 0;
            width: 0;
            height: 2px;
            background-color: var(--primary);
            transition: var(--transition);
        }
        
        .nav-links a:hover::after {
            width: 100%;
        }
        
        .auth-buttons {
            display: flex;
            gap: 15px;
        }
        
        .btn {
            padding: 10px 20px;
            border-radius: var(--border-radius);
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            border: none;
            font-size: 15px;
        }
        
        .btn-outline {
            background-color: transparent;
            border: 2px solid var(--primary);
            color: var(--primary);
        }
        
        .btn-primary {
            background-color: var(--primary);
            color: var(--white);
        }
        
        .btn-accent {
            background-color: var(--accent);
            color: var(--white);
        }
        
        .btn-outline:hover {
            background-color: var(--primary);
            color: var(--white);
        }
        
        .btn-primary:hover {
            background-color: #1d4ed8;
            transform: translateY(-2px);
            box-shadow: 0 6px 15px rgba(37, 99, 235, 0.3);
        }
        
        .btn-accent:hover {
            background-color: #d97706;
            transform: translateY(-2px);
            box-shadow: 0 6px 15px rgba(245, 158, 11, 0.3);
        }
        
        /* Hero区域样式 */
        .hero {
            background: linear-gradient(135deg, var(--primary) 0%, #1d4ed8 100%);
            color: var(--white);
            padding: 100px 0;
            text-align: center;
            position: relative;
            overflow: hidden;
        }
        
        .hero::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1200 120" preserveAspectRatio="none"><path d="M1200 120L0 16.48 0 0 1200 0 1200 120z" fill="%23ffffff" opacity="0.1"/></svg>') no-repeat bottom;
            background-size: cover;
        }
        
        .hero-content {
            position: relative;
            z-index: 1;
        }
        
        .hero h1 {
            font-size: 48px;
            margin-bottom: 20px;
            line-height: 1.2;
        }
        
        .hero p {
            font-size: 20px;
            max-width: 700px;
            margin: 0 auto 30px;
            color: rgba(255, 255, 255, 0.9);
        }
        
        .hero-buttons {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin-top: 30px;
        }
        
        .hero .btn {
            padding: 14px 30px;
            font-size: 16px;
        }
        
        .hero .btn-outline {
            border-color: var(--white);
            color: var(--white);
        }
        
        .hero .btn-outline:hover {
            background-color: var(--white);
            color: var(--primary);
        }
        
        /* 统计区域 */
        .stats {
            padding: 60px 0;
            background-color: var(--light-bg);
        }
        
        .stats-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 30px;
        }
        
        .stat-item {
            text-align: center;
            padding: 30px 20px;
            background-color: var(--white);
            border-radius: var(--border-radius);
            box-shadow: var(--shadow);
        }
        
        .stat-number {
            font-size: 42px;
            font-weight: 700;
            color: var(--primary);
            margin-bottom: 10px;
        }
        
        .stat-label {
            color: var(--medium-text);
            font-size: 18px;
        }
        
        /* 特性区域样式 */
        .features {
            padding: 100px 0;
        }
        
        .section-title {
            text-align: center;
            margin-bottom: 60px;
        }
        
        .section-title h2 {
            font-size: 36px;
            color: var(--primary);
            margin-bottom: 15px;
        }
        
        .section-title p {
            color: var(--medium-text);
            max-width: 600px;
            margin: 0 auto;
        }
        
        .features-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 30px;
        }
        
        .feature-card {
            background-color: var(--white);
            border-radius: var(--border-radius);
            padding: 40px 30px;
            text-align: center;
            box-shadow: var(--shadow);
            transition: var(--transition);
            border-top: 4px solid var(--primary);
        }
        
        .feature-card:hover {
            transform: translateY(-10px);
            box-shadow: 0 12px 25px rgba(0, 0, 0, 0.15);
        }
        
        .feature-icon {
            width: 80px;
            height: 80px;
            background-color: rgba(37, 99, 235, 0.1);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            margin: 0 auto 25px;
            color: var(--primary);
            font-size: 32px;
        }
        
        .feature-card h3 {
            font-size: 22px;
            margin-bottom: 15px;
            color: var(--primary);
        }
        
        .feature-card p {
            color: var(--medium-text);
        }
        
        /* 科目展示区域 */
        .subjects {
            padding: 100px 0;
            background-color: var(--light-bg);
        }
        
        .subjects-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 30px;
        }
        
        .subject-card {
            background-color: var(--white);
            border-radius: var(--border-radius);
            overflow: hidden;
            box-shadow: var(--shadow);
            transition: var(--transition);
            text-align: center;
        }
        
        .subject-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 10px 20px rgba(0, 0, 0, 0.12);
        }
        
        .subject-icon {
            height: 120px;
            background: linear-gradient(135deg, var(--primary) 0%, #1d4ed8 100%);
            display: flex;
            align-items: center;
            justify-content: center;
            color: var(--white);
            font-size: 48px;
        }
        
        .subject-content {
            padding: 25px;
        }
        
        .subject-content h3 {
            font-size: 20px;
            margin-bottom: 10px;
            color: var(--primary);
        }
        
        .subject-content p {
            color: var(--medium-text);
            margin-bottom: 20px;
        }
        
        /* 题库展示区域 */
        .question-bank {
            padding: 100px 0;
        }
        
        .bank-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            gap: 30px;
        }
        
        .bank-card {
            border-radius: var(--border-radius);
            overflow: hidden;
            box-shadow: var(--shadow);
            transition: var(--transition);
        }
        
        .bank-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 10px 20px rgba(0, 0, 0, 0.12);
        }
        
        .bank-header {
            background: linear-gradient(135deg, var(--primary) 0%, #1d4ed8 100%);
            color: var(--white);
            padding: 20px;
            text-align: center;
        }
        
        .bank-header h3 {
            font-size: 20px;
            margin-bottom: 5px;
        }
        
        .bank-content {
            padding: 25px;
            background-color: var(--white);
        }
        
        .bank-stats {
            display: flex;
            justify-content: space-between;
            margin-bottom: 20px;
        }
        
        .stat {
            text-align: center;
        }
        
        .stat-value {
            font-weight: 700;
            color: var(--primary);
            font-size: 18px;
        }
        
        .stat-label {
            font-size: 14px;
            color: var(--medium-text);
        }
        
        .bank-features {
            list-style: none;
            margin-bottom: 20px;
        }
        
        .bank-features li {
            padding: 8px 0;
            border-bottom: 1px solid #eee;
            color: var(--medium-text);
        }
        
        .bank-features li:last-child {
            border-bottom: none;
        }
        
        .bank-features li i {
            color: var(--secondary);
            margin-right: 10px;
        }
        
        /* CTA区域 */
        .cta {
            background: linear-gradient(135deg, var(--primary) 0%, #1d4ed8 100%);
            color: var(--white);
            padding: 80px 0;
            text-align: center;
        }
        
        .cta h2 {
            font-size: 36px;
            margin-bottom: 20px;
        }
        
        .cta p {
            font-size: 18px;
            max-width: 700px;
            margin: 0 auto 30px;
            color: rgba(255, 255, 255, 0.9);
        }
        
        /* 页脚样式 */
        footer {
            background-color: var(--dark-text);
            color: var(--white);
            padding: 60px 0 30px;
        }
        
        .footer-content {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 40px;
            margin-bottom: 40px;
        }
        
        .footer-column h3 {
            font-size: 18px;
            margin-bottom: 25px;
            position: relative;
            padding-bottom: 10px;
        }
        
        .footer-column h3::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 0;
            width: 40px;
            height: 2px;
            background-color: var(--accent);
        }
        
        .footer-links {
            list-style: none;
        }
        
        .footer-links li {
            margin-bottom: 12px;
        }
        
        .footer-links a {
            color: rgba(255, 255, 255, 0.7);
            text-decoration: none;
            transition: var(--transition);
        }
        
        .footer-links a:hover {
            color: var(--accent);
            padding-left: 5px;
        }
        
        .footer-bottom {
            border-top: 1px solid rgba(255, 255, 255, 0.1);
            padding-top: 30px;
            text-align: center;
            color: rgba(255, 255, 255, 0.6);
            font-size: 14px;
        }
        
        /* 响应式设计 */
        @media (max-width: 768px) {
            .navbar {
                flex-direction: column;
                padding: 15px 0;
            }
            
            .nav-links {
                margin: 20px 0;
                flex-wrap: wrap;
                justify-content: center;
            }
            
            .nav-links li {
                margin: 0 10px 10px;
            }
            
            .hero h1 {
                font-size: 36px;
            }
            
            .hero p {
                font-size: 18px;
            }
            
            .hero-buttons {
                flex-direction: column;
                align-items: center;
            }
            
            .hero-buttons .btn {
                width: 100%;
                max-width: 300px;
            }
            
            .features, .subjects, .question-bank, .cta {
                padding: 60px 0;
            }
            
            .section-title h2 {
                font-size: 28px;
            }
        }
.nav-menu {
  list-style: none;
  padding: 0;
}

.nav-menu li {
  position: relative;
  border-bottom: 1px solid #f1f1f1;
}

.has-submenu > a::after {
  content: '\f054';
  font-family: 'Font Awesome 5 Free';
  margin-left: auto;
}

.submenu {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.5s ease;
}

.has-submenu:hover .submenu {
  max-height: 500px;
}