/* ========================================
   保利威官网样式表 - 原生CSS
   作者: AI Assistant
   说明: 响应式企业官网样式
======================================== */

/* CSS变量定义 */
:root {
    /* 主色调 */
    --primary-color: #0066FF;
    --primary-dark: #0052CC;
    --primary-light: #3385FF;
    
    /* 辅助色 */
    --secondary-color: #00C6FF;
    --accent-color: #FF6B35;
    
    /* 文字颜色 */
    --text-primary: #1A1A1A;
    --text-secondary: #666666;
    --text-light: #999999;
    --text-white: #FFFFFF;
    
    /* 背景色 */
    --bg-white: #FFFFFF;
    --bg-light: #F5F7FA;
    --bg-dark: #1A1A1A;
    --bg-blue: #0066FF;
    
    /* 边框 */
    --border-color: #E8E8E8;
    --border-radius: 8px;
    --border-radius-lg: 16px;
    
    /* 阴影 */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.16);
    
    /* 过渡 */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* 容器宽度 */
    --container-max-width: 1200px;
    --container-padding: 24px;
}

/* 重置样式 */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-white);
    overflow-x: hidden;
}

ul, ol {
    list-style: none;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color var(--transition-fast);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

button {
    cursor: pointer;
    border: none;
    background: none;
    font-family: inherit;
}

/* 容器 */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* ========================================
   按钮样式
======================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 24px;
    font-size: 14px;
    font-weight: 500;
    border-radius: var(--border-radius);
    transition: all var(--transition-fast);
    white-space: nowrap;
}

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

.btn-primary:hover {
    background-color: var(--primary-dark);
    border-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

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

.btn-login:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

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

.btn-white:hover {
    background-color: transparent;
    color: var(--text-white);
}

/* ========================================
   导航栏
======================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: var(--bg-white);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: box-shadow var(--transition-fast);
}

.header.scrolled {
    box-shadow: var(--shadow-md);
}

.navbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

/* Logo */
.logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    font-size: 20px;
}

.logo-icon {
    color: var(--primary-color);
    letter-spacing: 1px;
}

.logo-text {
    color: var(--text-primary);
}

/* 导航菜单 */
.nav-menu {
    display: flex;
    align-items: center;
    gap: 32px;
}

.nav-item {
    position: relative;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 14px;
    color: var(--text-primary);
    padding: 8px 0;
    transition: color var(--transition-fast);
}

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

.nav-link .arrow {
    font-size: 10px;
    transition: transform var(--transition-fast);
}

.nav-item:hover .arrow {
    transform: rotate(180deg);
}

/* 下拉菜单 */
.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    background-color: var(--bg-white);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-lg);
    padding: 12px 0;
    min-width: 180px;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-fast);
    z-index: 100;
}

.nav-item:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.dropdown-menu a {
    display: block;
    padding: 10px 20px;
    font-size: 14px;
    color: var(--text-secondary);
    transition: all var(--transition-fast);
}

.dropdown-menu a:hover {
    color: var(--primary-color);
    background-color: var(--bg-light);
}

/* 右侧功能区 */
.nav-right {
    display: flex;
    align-items: center;
    gap: 16px;
}

.phone {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 14px;
    color: var(--text-secondary);
}

.phone-icon {
    font-size: 16px;
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 8px;
    background: none;
    border: none;
    cursor: pointer;
}

.mobile-menu-btn span {
    display: block;
    width: 24px;
    height: 2px;
    background-color: var(--text-primary);
    transition: all var(--transition-fast);
}

.mobile-menu-btn.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-btn.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-btn.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* 移动端菜单 */
.mobile-menu {
    display: none;
    position: fixed;
    top: 70px;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: var(--bg-white);
    z-index: 999;
    padding: 24px;
    transform: translateX(100%);
    transition: transform var(--transition-normal);
}

.mobile-menu.active {
    transform: translateX(0);
}

.mobile-nav-menu {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.mobile-nav-menu a {
    display: block;
    padding: 16px;
    font-size: 16px;
    color: var(--text-primary);
    border-bottom: 1px solid var(--border-color);
}

.mobile-nav-bottom {
    margin-top: 32px;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.mobile-nav-bottom .btn {
    width: 100%;
    padding: 14px;
    font-size: 16px;
}

/* ========================================
   Banner区域
======================================== */
.hero-banner {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    padding: 120px 0 80px;
    margin-top: 70px;
    position: relative;
    overflow: hidden;
}

.hero-banner::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 1440 320"><path fill="rgba(255,255,255,0.05)" d="M0,96L48,112C96,128,192,160,288,160C384,160,480,128,576,122.7C672,117,768,139,864,154.7C960,171,1056,181,1152,165.3C1248,149,1344,107,1392,85.3L1440,64L1440,320L1392,320C1344,320,1248,320,1152,320C1056,320,960,320,864,320C768,320,672,320,576,320C480,320,384,320,288,320C192,320,96,320,48,320L0,320Z"></path></svg>') no-repeat bottom;
    background-size: cover;
}

.hero-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 48px;
    align-items: center;
    position: relative;
    z-index: 1;
}

/* 视频展示区 */
.hero-video {
    position: relative;
}

.video-container {
    position: relative;
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
}

.video-thumb {
    width: 100%;
    height: auto;
    display: block;
}

.video-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(to top, rgba(0,0,0,0.7) 0%, rgba(0,0,0,0.2) 50%, transparent 100%);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 24px;
}

.play-btn {
    width: 80px;
    height: 80px;
    background-color: rgba(255,255,255,0.95);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    cursor: pointer;
}

.play-btn:hover {
    transform: scale(1.1);
    background-color: var(--text-white);
    box-shadow: 0 0 30px rgba(255,255,255,0.5);
}

.play-icon {
    font-size: 28px;
    color: var(--primary-color);
    margin-left: 6px;
}

.video-info {
    position: absolute;
    bottom: 60px;
    left: 24px;
    color: var(--text-white);
}

.video-title {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 4px;
}

.video-subtitle {
    font-size: 14px;
    opacity: 0.9;
}

.video-tags {
    position: absolute;
    bottom: 20px;
    left: 24px;
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.video-tags .tag {
    background-color: rgba(255,255,255,0.2);
    color: var(--text-white);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 12px;
    backdrop-filter: blur(4px);
}

/* 右侧文字 */
.hero-text {
    color: var(--text-white);
    text-align: right;
}

.hero-title {
    font-size: 48px;
    font-weight: 700;
    margin-bottom: 16px;
    text-shadow: 0 2px 10px rgba(0,0,0,0.2);
}

.hero-desc {
    font-size: 16px;
    opacity: 0.9;
}

/* ========================================
   数据统计区
======================================== */
.stats-section {
    background-color: var(--bg-light);
    padding: 60px 0;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 32px;
}

.stat-item {
    text-align: center;
    padding: 32px 24px;
    background-color: var(--bg-white);
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-fast);
    position: relative;
    overflow: hidden;
}

.stat-item:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.stat-item.highlight {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-light) 100%);
    color: var(--text-white);
}

.stat-item.highlight .stat-label,
.stat-item.highlight .unit {
    color: rgba(255,255,255,0.9);
}

.stat-label {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 12px;
}

.stat-number {
    display: flex;
    align-items: baseline;
    justify-content: center;
    gap: 4px;
    margin-bottom: 12px;
}

.stat-number .number {
    font-size: 48px;
    font-weight: 700;
    color: var(--primary-color);
    line-height: 1;
}

.stat-item.highlight .number {
    color: var(--text-white);
}

.stat-number .unit {
    font-size: 16px;
    color: var(--text-secondary);
    font-weight: 500;
}

.stat-icon {
    font-size: 32px;
    opacity: 0.8;
}

/* ========================================
   核心产品区
======================================== */
.products-section {
    padding: 80px 0;
    background-color: var(--bg-white);
}

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-title {
    font-size: 36px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.section-subtitle {
    font-size: 18px;
    color: var(--text-secondary);
}

.products-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.product-card {
    background-color: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: 32px 24px;
    transition: all var(--transition-fast);
    position: relative;
    overflow: hidden;
}

.product-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    transform: scaleX(0);
    transition: transform var(--transition-fast);
}

.product-card:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-md);
    transform: translateY(-4px);
}

.product-card:hover::before {
    transform: scaleX(1);
}

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

.product-title {
    font-size: 20px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.product-desc {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 20px;
    line-height: 1.6;
}

.product-features {
    margin-bottom: 24px;
}

.product-features li {
    font-size: 13px;
    color: var(--text-light);
    padding: 6px 0;
    padding-left: 16px;
    position: relative;
}

.product-features li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: 600;
}

.product-link {
    font-size: 14px;
    color: var(--primary-color);
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    gap: 4px;
    transition: gap var(--transition-fast);
}

.product-link:hover {
    gap: 8px;
}

/* ========================================
   解决方案区
======================================== */
.solutions-section {
    padding: 80px 0;
    background-color: var(--bg-light);
}

.solutions-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}

.solution-card {
    background-color: var(--bg-white);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-fast);
}

.solution-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.solution-image {
    width: 100%;
    height: 200px;
    overflow: hidden;
}

.solution-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-slow);
}

.solution-card:hover .solution-image img {
    transform: scale(1.05);
}

.solution-content {
    padding: 24px;
}

.solution-title {
    font-size: 18px;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.solution-desc {
    font-size: 14px;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 16px;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.solution-tags {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.solution-tags .tag {
    background-color: var(--bg-light);
    color: var(--text-secondary);
    padding: 4px 12px;
    border-radius: 4px;
    font-size: 12px;
}

/* ========================================
   行业解决方案
======================================== */
.industries-section {
    padding: 80px 0;
    background-color: var(--bg-white);
}

.industries-tabs {
    display: flex;
    justify-content: center;
    gap: 8px;
    margin-bottom: 48px;
    flex-wrap: wrap;
}

.tab-btn {
    padding: 12px 24px;
    font-size: 14px;
    color: var(--text-secondary);
    background-color: var(--bg-light);
    border: none;
    border-radius: 30px;
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.tab-btn:hover {
    background-color: var(--border-color);
    color: var(--text-primary);
}

.tab-btn.active {
    background-color: var(--primary-color);
    color: var(--text-white);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
    animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.industry-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    align-items: center;
    background-color: var(--bg-light);
    border-radius: var(--border-radius-lg);
    padding: 48px;
}

.industry-info h3 {
    font-size: 28px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 24px;
}

.industry-list {
    margin-bottom: 32px;
}

.industry-list li {
    font-size: 16px;
    color: var(--text-secondary);
    padding: 12px 0;
    padding-left: 28px;
    position: relative;
    border-bottom: 1px dashed var(--border-color);
}

.industry-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: 600;
    width: 20px;
    height: 20px;
    background-color: rgba(0,102,255,0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
}

.industry-image {
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-md);
}

.industry-image img {
    width: 100%;
    height: auto;
}

/* ========================================
   CTA区域
======================================== */
.cta-section {
    padding: 100px 0;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.cta-section::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 1px, transparent 1px);
    background-size: 30px 30px;
    opacity: 0.3;
}

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

.cta-title {
    font-size: 36px;
    font-weight: 700;
    color: var(--text-white);
    margin-bottom: 16px;
}

.cta-desc {
    font-size: 18px;
    color: rgba(255,255,255,0.9);
    margin-bottom: 32px;
}

/* ========================================
   侧边悬浮工具栏
======================================== */
.sidebar-tools {
    position: fixed;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    background-color: var(--bg-white);
    box-shadow: var(--shadow-md);
    border-radius: var(--border-radius) 0 0 var(--border-radius);
    z-index: 998;
    overflow: hidden;
}

.tool-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 16px 12px;
    cursor: pointer;
    transition: all var(--transition-fast);
    border-bottom: 1px solid var(--border-color);
}

.tool-item:last-child {
    border-bottom: none;
}

.tool-item:hover {
    background-color: var(--primary-color);
}

.tool-item:hover .tool-icon,
.tool-item:hover .tool-text {
    color: var(--text-white);
}

.tool-icon {
    font-size: 24px;
    margin-bottom: 4px;
}

.tool-text {
    font-size: 12px;
    color: var(--text-secondary);
    writing-mode: vertical-rl;
    text-orientation: mixed;
}

/* ========================================
   Footer
======================================== */
.footer {
    background-color: var(--bg-dark);
    color: var(--text-white);
    padding: 80px 0 32px;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr 1fr;
    gap: 48px;
    margin-bottom: 48px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    font-size: 20px;
    margin-bottom: 20px;
}

.footer-logo .logo-icon {
    color: var(--primary-color);
}

.footer-desc {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: 20px;
}

.footer-contact p {
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 8px;
}

.footer-title {
    font-size: 16px;
    font-weight: 600;
    color: var(--text-white);
    margin-bottom: 20px;
}

.footer-links li {
    margin-bottom: 12px;
}

.footer-links a {
    font-size: 14px;
    color: var(--text-light);
    transition: color var(--transition-fast);
}

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

.footer-bottom {
    padding-top: 32px;
    border-top: 1px solid rgba(255,255,255,0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

.copyright {
    font-size: 13px;
    color: var(--text-light);
}

.footer-bottom-links {
    display: flex;
    gap: 24px;
}

.footer-bottom-links a {
    font-size: 13px;
    color: var(--text-light);
}

.footer-bottom-links a:hover {
    color: var(--text-white);
}

/* ========================================
   响应式设计 - 移动端适配
======================================== */
@media (max-width: 1200px) {
    .products-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .solutions-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 992px) {
    .nav-menu,
    .nav-right {
        display: none;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .mobile-menu {
        display: block;
    }
    
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-text {
        text-align: center;
    }
    
    .hero-title {
        font-size: 36px;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .industry-content {
        grid-template-columns: 1fr;
    }
    
    .industry-image {
        order: -1;
    }
    
    .footer-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-about {
        grid-column: span 2;
    }
}

@media (max-width: 768px) {
    :root {
        --container-padding: 16px;
    }
    
    .section-title {
        font-size: 28px;
    }
    
    .products-grid {
        grid-template-columns: 1fr;
    }
    
    .solutions-grid {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
        gap: 16px;
    }
    
    .stat-item {
        padding: 24px;
    }
    
    .stat-number .number {
        font-size: 36px;
    }
    
    .industries-tabs {
        gap: 8px;
    }
    
    .tab-btn {
        padding: 10px 16px;
        font-size: 13px;
    }
    
    .industry-content {
        padding: 24px;
    }
    
    .industry-info h3 {
        font-size: 22px;
    }
    
    .cta-title {
        font-size: 28px;
    }
    
    .sidebar-tools {
        display: none;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }
    
    .footer-about {
        grid-column: span 1;
    }
    
    .footer-bottom {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero-banner {
        padding: 100px 0 60px;
    }
    
    .hero-title {
        font-size: 28px;
    }
    
    .video-info {
        bottom: 50px;
    }
    
    .video-title {
        font-size: 16px;
    }
    
    .play-btn {
        width: 60px;
        height: 60px;
    }
    
    .play-icon {
        font-size: 20px;
    }
    
    .section-header {
        margin-bottom: 40px;
    }
    
    .product-card,
    .solution-card,
    .stat-item {
        padding: 24px 20px;
    }
    
    .cta-section {
        padding: 60px 0;
    }
    
    .cta-title {
        font-size: 24px;
    }
}

/* ========================================
   动画效果
======================================== */
@keyframes countUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.stat-item {
    animation: countUp 0.6s ease forwards;
}

.stat-item:nth-child(1) { animation-delay: 0.1s; }
.stat-item:nth-child(2) { animation-delay: 0.2s; }
.stat-item:nth-child(3) { animation-delay: 0.3s; }
.stat-item:nth-child(4) { animation-delay: 0.4s; }

/* 滚动显示动画 */
.scroll-reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.scroll-reveal.revealed {
    opacity: 1;
    transform: translateY(0);
}