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

body {
    font-family: 'Segoe UI', Arial, sans-serif;
    line-height: 1.6;
    color: #1a1a2e;
    background: #f8f9fa;
    transition: background 0.3s, color 0.3s;
}

body.dark-mode {
    background: #0f0f1a;
    color: #e0e0e0;
}

a {
    text-decoration: none;
    color: inherit;
}

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

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

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}

/* 导航 */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(10px);
    z-index: 1000;
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
    transition: background 0.3s;
}

.dark-mode .navbar {
    background: rgba(15, 15, 26, 0.9);
}

.nav-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    font-size: 1.8rem;
    font-weight: 700;
    background: linear-gradient(135deg, #1a73e8, #00c9a7);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    gap: 25px;
    list-style: none;
    font-weight: 500;
}

.nav-links a {
    position: relative;
    padding: 5px 0;
    transition: color 0.3s;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: #1a73e8;
    transition: width 0.3s;
}

.nav-links a:hover::after {
    width: 100%;
}

.dark-mode .nav-links a::after {
    background: #00c9a7;
}

.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
}

.menu-toggle span {
    width: 28px;
    height: 3px;
    background: #1a73e8;
    border-radius: 3px;
    transition: 0.3s;
}

.dark-mode .menu-toggle span {
    background: #e0e0e0;
}

/* Hero */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #e8f0fe 0%, #f0fdf4 50%, #e0f7fa 100%);
    position: relative;
    overflow: hidden;
    padding-top: 80px;
}

.dark-mode .hero {
    background: linear-gradient(135deg, #0a1628 0%, #1a1a2e 50%, #0f1f1a 100%);
}

.hero-content {
    text-align: center;
    z-index: 2;
    padding: 40px 20px;
}

.hero h1 {
    font-size: 4rem;
    font-weight: 800;
    background: linear-gradient(135deg, #1a73e8, #00c9a7);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 20px;
    animation: fadeInUp 1s ease;
}

.hero p {
    font-size: 1.3rem;
    color: #555;
    max-width: 700px;
    margin: 0 auto 30px;
}

.dark-mode .hero p {
    color: #aaa;
}

.hero-btn {
    display: inline-block;
    padding: 16px 40px;
    background: linear-gradient(135deg, #1a73e8, #00c9a7);
    color: #fff;
    border-radius: 50px;
    font-size: 1.1rem;
    font-weight: 600;
    transition: transform 0.3s, box-shadow 0.3s;
}

.hero-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 30px rgba(26, 115, 232, 0.4);
}

/* 通用模块 */
section {
    padding: 80px 0;
}

.section-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 50px;
    position: relative;
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 4px;
    background: linear-gradient(135deg, #1a73e8, #00c9a7);
    margin: 15px auto 0;
    border-radius: 2px;
}

.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
    align-items: center;
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.grid-4 {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 25px;
}

.card {
    background: #fff;
    border-radius: 20px;
    padding: 30px;
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.06);
    backdrop-filter: blur(10px);
    transition: transform 0.3s, box-shadow 0.3s;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.dark-mode .card {
    background: rgba(30, 30, 50, 0.8);
    border-color: rgba(255, 255, 255, 0.05);
}

.card:hover {
    transform: translateY(-8px);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.12);
}

.card-icon {
    width: 60px;
    height: 60px;
    border-radius: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 20px;
    font-size: 2rem;
}

.text-center {
    text-align: center;
}

.mt-20 {
    margin-top: 20px;
}

.mb-20 {
    margin-bottom: 20px;
}

.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* 数据展示 */
.stats {
    background: linear-gradient(135deg, #1a73e8, #00c9a7);
    color: #fff;
    padding: 60px 0;
}

.stats .grid-4 {
    text-align: center;
}

.stat-number {
    font-size: 3rem;
    font-weight: 800;
}

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

/* 客户评价 */
.testimonial-card {
    background: #fff;
    border-radius: 20px;
    padding: 30px;
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.05);
    position: relative;
}

.dark-mode .testimonial-card {
    background: rgba(30, 30, 50, 0.8);
}

.testimonial-card::before {
    content: '"';
    font-size: 4rem;
    color: #1a73e8;
    opacity: 0.2;
    position: absolute;
    top: 10px;
    left: 20px;
}

/* FAQ */
.faq-item {
    border-bottom: 1px solid #e0e0e0;
    padding: 15px 0;
    cursor: pointer;
}

.dark-mode .faq-item {
    border-color: #333;
}

.faq-question {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 600;
    font-size: 1.1rem;
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease;
    padding-top: 0;
    color: #666;
}

.dark-mode .faq-answer {
    color: #aaa;
}

.faq-item.active .faq-answer {
    max-height: 300px;
    padding-top: 15px;
}

.faq-icon {
    transition: transform 0.3s;
}

.faq-item.active .faq-icon {
    transform: rotate(45deg);
}

/* Footer */
footer {
    background: #1a1a2e;
    color: #ccc;
    padding: 60px 0 30px;
}

.dark-mode footer {
    background: #0a0a15;
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 40px;
    margin-bottom: 40px;
}

.footer-bottom {
    border-top: 1px solid #333;
    padding-top: 20px;
    text-align: center;
    font-size: 0.9rem;
}

/* 响应式 */
@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: absolute;
        top: 70px;
        left: 0;
        width: 100%;
        background: rgba(255, 255, 255, 0.98);
        flex-direction: column;
        padding: 20px;
        gap: 15px;
        box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    }

    .dark-mode .nav-links {
        background: rgba(15, 15, 26, 0.98);
    }

    .nav-links.active {
        display: flex;
    }

    .menu-toggle {
        display: flex;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }

    .footer-grid {
        grid-template-columns: 1fr 1fr;
    }

    section {
        padding: 50px 0;
    }

    .section-title {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 2rem;
    }

    .footer-grid {
        grid-template-columns: 1fr;
    }
}

/* 动画 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(40px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 面包屑 */
.breadcrumb {
    padding: 15px 0;
    font-size: 0.9rem;
    color: #888;
}

.dark-mode .breadcrumb {
    color: #aaa;
}

.breadcrumb span {
    margin: 0 5px;
}

/* 搜索 */
.search-box {
    max-width: 400px;
    margin: 20px auto;
    display: flex;
    gap: 10px;
}

.search-box input {
    flex: 1;
    padding: 12px 20px;
    border: 2px solid #e0e0e0;
    border-radius: 30px;
    font-size: 1rem;
    outline: none;
    transition: border 0.3s;
}

.search-box input:focus {
    border-color: #1a73e8;
}

.dark-mode .search-box input {
    background: #1a1a2e;
    border-color: #333;
    color: #e0e0e0;
}

.search-box button {
    padding: 12px 25px;
    background: linear-gradient(135deg, #1a73e8, #00c9a7);
    color: #fff;
    border: none;
    border-radius: 30px;
    cursor: pointer;
    font-weight: 600;
    transition: transform 0.3s;
}

.search-box button:hover {
    transform: scale(1.05);
}

/* 返回顶部 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: linear-gradient(135deg, #1a73e8, #00c9a7);
    color: #fff;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.5rem;
    box-shadow: 0 5px 20px rgba(26, 115, 232, 0.4);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 999;
    transition: transform 0.3s;
}

.back-to-top:hover {
    transform: scale(1.1);
}

.back-to-top.show {
    display: flex;
}

/* 暗黑切换 */
.dark-toggle {
    position: fixed;
    bottom: 30px;
    left: 30px;
    width: 50px;
    height: 50px;
    background: #1a1a2e;
    color: #fff;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.3rem;
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.2);
    z-index: 999;
    transition: transform 0.3s;
}

.dark-mode .dark-toggle {
    background: #e0e0e0;
    color: #1a1a2e;
}

.dark-toggle:hover {
    transform: scale(1.1);
}

/* Banner轮播 */
.carousel {
    position: relative;
    overflow: hidden;
    border-radius: 20px;
    margin: 30px 0;
}

.carousel-inner {
    display: flex;
    transition: transform 0.5s ease;
}

.carousel-item {
    min-width: 100%;
    padding: 60px 40px;
    text-align: center;
    background: linear-gradient(135deg, #e8f0fe, #f0fdf4);
}

.dark-mode .carousel-item {
    background: linear-gradient(135deg, #1a1a2e, #0f1f1a);
}

.carousel-btn {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: rgba(255, 255, 255, 0.8);
    border: none;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    cursor: pointer;
    font-size: 1.2rem;
    color: #1a73e8;
    transition: background 0.3s;
}

.carousel-btn:hover {
    background: #fff;
}

.carousel-prev {
    left: 15px;
}

.carousel-next {
    right: 15px;
}
```