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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #f5f7fa;
    color: #333;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 导航栏 */
.navbar {
    background: white;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 60px;
}

.nav-brand a {
    font-size: 20px;
    font-weight: bold;
    color: #667eea;
    text-decoration: none;
}

.nav-menu {
    display: flex;
    gap: 20px;
    align-items: center;
}

.nav-menu a {
    color: #666;
    text-decoration: none;
    transition: color 0.3s;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: #667eea;
}

/* Hero 区域 */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 80px 0;
    text-align: center;
}

.hero h1 {
    font-size: 48px;
    margin-bottom: 20px;
}

.hero p {
    font-size: 18px;
    opacity: 0.9;
    margin-bottom: 30px;
}

.hero-buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
}

/* 特性区域 */
.features {
    padding: 60px 0;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.feature-card {
    background: white;
    border-radius: 12px;
    padding: 30px;
    text-align: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    transition: transform 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
}

.feature-icon {
    font-size: 48px;
    margin-bottom: 20px;
}

.feature-card h3 {
    margin-bottom: 15px;
    color: #333;
}

.feature-card p {
    color: #666;
    line-height: 1.6;
}

/* 按钮 */
.btn {
    display: inline-block;
    padding: 12px 24px;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s;
    border: none;
    cursor: pointer;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102,126,234,0.4);
}

.btn-secondary {
    background: rgba(255,255,255,0.2);
    color: white;
    border: 1px solid white;
}

.btn-secondary:hover {
    background: rgba(255,255,255,0.3);
}

.btn-block {
    width: 100%;
}

/* 认证页面 */
.auth-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    padding: 20px;
}

.auth-card {
    background: white;
    border-radius: 20px;
    padding: 40px;
    width: 100%;
    max-width: 400px;
    box-shadow: 0 20px 40px rgba(0,0,0,0.1);
}

.auth-header {
    text-align: center;
    margin-bottom: 30px;
}

.auth-header h2 {
    font-size: 28px;
    color: #333;
    margin-bottom: 10px;
}

.auth-header p {
    color: #666;
}

/* 表单 */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: #333;
}

.form-group input {
    width: 100%;
    padding: 12px 15px;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 14px;
    transition: all 0.3s;
    outline: none;
}

.form-group input:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102,126,234,0.1);
}

.remember {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.remember label {
    display: flex;
    align-items: center;
    gap: 5px;
    cursor: pointer;
}

/* 提示框 */
.alert {
    padding: 12px 16px;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: 14px;
}

.alert-success {
    background-color: #d4edda;
    color: #155724;
    border-left: 4px solid #28a745;
}

.alert-danger {
    background-color: #f8d7da;
    color: #721c24;
    border-left: 4px solid #dc3545;
}

.alert-info {
    background-color: #d1ecf1;
    color: #0c5460;
    border-left: 4px solid #17a2b8;
}

/* 页脚 */
footer {
    background: #2c3e50;
    color: white;
    padding: 30px 0;
    text-align: center;
    margin-top: 60px;
}

/* 响应式 */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 32px;
    }
    
    .hero p {
        font-size: 16px;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .auth-card {
        padding: 30px 20px;
    }
}