/* 全局样式 */
:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --success-color: #48bb78;
    --error-color: #f56565;
    --warning-color: #ed8936;
    --info-color: #4299e1;
    --text-primary: #2d3748;
    --text-secondary: #718096;
    --text-muted: #a0aec0;
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-tertiary: #edf2f7;
    --border-color: #e2e8f0;
    --border-light: #f1f5f9;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.12);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px rgba(0,0,0,0.1);
    --shadow-xl: 0 20px 25px rgba(0,0,0,0.1);
    --transition: all 0.3s ease;
    --border-radius: 8px;
    --border-radius-lg: 12px;
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

.container-fluid {
    width: 100%;
    padding: 0 20px;
}

/* 网格系统 */
.row {
    display: flex;
    flex-wrap: wrap;
    margin: 0 -10px;
}

.col {
    flex: 1;
    padding: 0 10px;
}

.col-1 { flex: 0 0 8.333333%; }
.col-2 { flex: 0 0 16.666667%; }
.col-3 { flex: 0 0 25%; }
.col-4 { flex: 0 0 33.333333%; }
.col-5 { flex: 0 0 41.666667%; }
.col-6 { flex: 0 0 50%; }
.col-7 { flex: 0 0 58.333333%; }
.col-8 { flex: 0 0 66.666667%; }
.col-9 { flex: 0 0 75%; }
.col-10 { flex: 0 0 83.333333%; }
.col-11 { flex: 0 0 91.666667%; }
.col-12 { flex: 0 0 100%; }

/* 卡片组件 */
.card {
    background: var(--bg-primary);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    transition: var(--transition);
}

.card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.card-header {
    padding: 20px;
    border-bottom: 1px solid var(--border-color);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
}

.card-body {
    padding: 20px;
}

.card-footer {
    padding: 15px 20px;
    border-top: 1px solid var(--border-color);
    background: var(--bg-secondary);
}

/* 按钮组件 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 500;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    min-height: 44px;
    gap: 8px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: white;
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-dark), var(--primary-color));
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--border-color);
}

.btn-success {
    background: var(--success-color);
    color: white;
}

.btn-warning {
    background: var(--warning-color);
    color: white;
}

.btn-error {
    background: var(--error-color);
    color: white;
}

.btn-outline {
    background: transparent;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
}

.btn-outline:hover {
    background: var(--primary-color);
    color: white;
}

.btn-lg {
    padding: 16px 32px;
    font-size: 16px;
}

.btn-sm {
    padding: 8px 16px;
    font-size: 12px;
}

.btn-block {
    width: 100%;
}

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

.form-label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    color: var(--text-primary);
}

.form-input {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 14px;
    transition: var(--transition);
    background: var(--bg-primary);
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.form-input::placeholder {
    color: var(--text-secondary);
}

.form-textarea {
    resize: vertical;
    min-height: 100px;
}

.form-select {
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%23333' d='M6 9L1 4h10z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    padding-right: 36px;
}

/* 导航组件 */
.navbar {
    background: var(--bg-primary);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 0;
}

.navbar-brand {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
    text-decoration: none;
    transition: var(--transition);
}

.navbar-brand:hover {
    color: var(--primary-dark);
}

.navbar-nav {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
}

.nav-link:hover {
    color: var(--primary-color);
}

.nav-link.active {
    color: var(--primary-color);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
}

/* 英雄区域 */
.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: 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 0 100 100"><defs><pattern id="grain" width="100" height="100" patternUnits="userSpaceOnUse"><circle cx="50" cy="50" r="1" fill="rgba(255,255,255,0.1)"/></pattern></defs><rect width="100" height="100" fill="url(%23grain)"/></svg>');
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: bold;
    margin-bottom: 1.5rem;
    animation: fadeInUp 1s ease-out;
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
    animation: fadeInUp 1s ease-out 0.2s both;
}

/* 特性网格 */
.features {
    padding: 80px 0;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.feature-card {
    text-align: center;
    padding: 2rem;
    border-radius: 12px;
    background: var(--bg-primary);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.feature-title {
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.feature-description {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* 统计数据 */
.stats {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 60px 0;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    text-align: center;
}

.stat-item {
    padding: 1rem;
}

.stat-number {
    font-size: 3rem;
    font-weight: bold;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1.1rem;
    opacity: 0.9;
}

/* 页脚 */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 40px 0 20px;
    margin-top: 80px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: var(--transition);
}

.footer-section a:hover {
    color: var(--primary-color);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

/* 动画 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

.fade-in {
    animation: fadeIn 0.6s ease-out;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.1rem;
    }
    
    .navbar-nav {
        flex-direction: column;
        gap: 1rem;
    }
    
    .navbar-container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .features-grid,
    .stats-grid,
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .row {
        margin: 0 -5px;
    }
    
    .col {
        padding: 0 5px;
    }
}

/* 工具类 */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: 0.25rem; }
.mb-2 { margin-bottom: 0.5rem; }
.mb-3 { margin-bottom: 1rem; }
.mb-4 { margin-bottom: 1.5rem; }
.mb-5 { margin-bottom: 2rem; }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: 0.25rem; }
.mt-2 { margin-top: 0.5rem; }
.mt-3 { margin-top: 1rem; }
.mt-4 { margin-top: 1.5rem; }
.mt-5 { margin-top: 2rem; }

.p-0 { padding: 0; }
.p-1 { padding: 0.25rem; }
.p-2 { padding: 0.5rem; }
.p-3 { padding: 1rem; }
.p-4 { padding: 1.5rem; }
.p-5 { padding: 2rem; }

.d-none { display: none; }
.d-block { display: block; }
.d-flex { display: flex; }
.d-inline { display: inline; }
.d-inline-block { display: inline-block; }

.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.justify-around { justify-content: space-around; }
.align-center { align-items: center; }
.align-start { align-items: flex-start; }
.align-end { align-items: flex-end; }

.w-100 { width: 100%; }
.h-100 { height: 100%; }

.rounded { border-radius: 8px; }
.rounded-lg { border-radius: 12px; }
.rounded-xl { border-radius: 16px; }

.shadow-sm { box-shadow: var(--shadow-sm); }
.shadow-md { box-shadow: var(--shadow-md); }
.shadow-lg { box-shadow: var(--shadow-lg); }
.shadow-xl { box-shadow: var(--shadow-xl); }

/* 过渡效果 */
.transition { transition: var(--transition); }
.hover-lift:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

/* 加载动画 */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255,255,255,.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}