/* ==================== 全局样式 ==================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* 主色调 - 现代紫蓝渐变 */
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary-color: #8b5cf6;
    --accent-color: #06b6d4;
    
    /* 中性色 */
    --dark-color: #0f172a;
    --gray-dark: #1e293b;
    --gray-medium: #64748b;
    --gray-light: #cbd5e1;
    --light-color: #f8fafc;
    --white: #ffffff;
    
    /* 渐变色 */
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --gradient-accent: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --gradient-dark: linear-gradient(135deg, #434343 0%, #000000 100%);
    
    /* 阴影 */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.3);
    
    /* 字体 */
    --font-primary: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
    --font-heading: "PingFang SC", "Microsoft YaHei", sans-serif;
    
    /* 过渡效果 */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* 间距 */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    font-size: 16px;
    line-height: 1.6;
    color: var(--gray-dark);
    background-color: var(--white);
    overflow-x: hidden;
}

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

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

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

ul {
    list-style: none;
}

/* ==================== 导航栏 ==================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: var(--transition-base);
}

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

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

.nav-logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 700;
}

.logo-image {
    height: 45px;
    width: auto;
}

.logo-text {
    font-size: 22px;
    font-weight: 700;
    color: var(--dark-color);
    font-family: "Microsoft YaHei", "PingFang SC", "Hiragino Sans GB", "Helvetica Neue", Arial, sans-serif;
    letter-spacing: 2px;
}

.logo-icon {
    font-size: 24px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.logo-text {
    font-size: 18px;
    color: var(--dark-color);
}

.nav-list {
    display: flex;
    gap: 2rem;
}

.nav-link {
    font-weight: 500;
    color: var(--gray-dark);
    position: relative;
    padding: 0.5rem 0;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: var(--transition-base);
}

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

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

.nav-toggle {
    display: none;
    font-size: 24px;
    cursor: pointer;
    color: var(--dark-color);
}

/* ==================== 首页横幅 ==================== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    position: relative;
    overflow: hidden;
    padding-top: 70px;
}

.hero::before {
    content: '';
    position: absolute;
    width: 150%;
    height: 150%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 1px, transparent 1px);
    background-size: 50px 50px;
    animation: moveGrid 20s linear infinite;
}

@keyframes moveGrid {
    0% { transform: translate(0, 0); }
    100% { transform: translate(50px, 50px); }
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-content {
    color: var(--white);
}

.hero-title {
    display: flex;
    flex-direction: column;
    margin-bottom: 1.5rem;
}

.hero-title-main {
    font-size: 3.5rem;
    font-weight: 700;
    font-family: var(--font-heading);
    line-height: 1.2;
    margin-bottom: 0.5rem;
    animation: fadeInUp 0.8s ease;
}

.hero-title-sub {
    font-size: 2.5rem;
    font-weight: 600;
    opacity: 0.9;
    animation: fadeInUp 1s ease;
}

.hero-description {
    font-size: 1.125rem;
    line-height: 1.8;
    opacity: 0.95;
    margin-bottom: 2rem;
    animation: fadeInUp 1.2s ease;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    animation: fadeInUp 1.4s ease;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 2rem;
    font-weight: 600;
    border-radius: 50px;
    cursor: pointer;
    transition: var(--transition-base);
    border: none;
    font-size: 1rem;
}

.btn-primary {
    background: var(--white);
    color: var(--primary-color);
    box-shadow: var(--shadow-lg);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

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

.btn-outline:hover {
    background: var(--white);
    color: var(--primary-color);
    transform: translateY(-2px);
}

.btn-block {
    width: 100%;
    justify-content: center;
}

.hero-image {
    position: relative;
    height: 400px;
}

.hero-card {
    position: absolute;
    background: rgba(255, 255, 255, 0.15);
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: 20px;
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    color: var(--white);
    animation: float 3s ease-in-out infinite;
}

.hero-card i {
    font-size: 2rem;
}

.hero-card span {
    font-weight: 600;
    font-size: 1.125rem;
}

.card-1 {
    top: 10%;
    left: 0;
    animation-delay: 0s;
}

.card-2 {
    top: 40%;
    right: 10%;
    animation-delay: 1s;
}

.card-3 {
    bottom: 10%;
    left: 20%;
    animation-delay: 2s;
}

@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-20px); }
}

.hero-scroll {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
    color: var(--white);
    opacity: 0.8;
    animation: bounce 2s ease-in-out infinite;
}

.hero-scroll i {
    font-size: 1.5rem;
}

@keyframes bounce {
    0%, 100% { transform: translateX(-50%) translateY(0); }
    50% { transform: translateX(-50%) translateY(10px); }
}

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

/* ==================== 区块通用样式 ==================== */
section {
    padding: var(--spacing-xl) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.section-tag {
    display: inline-block;
    padding: 0.5rem 1.5rem;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(118, 75, 162, 0.1));
    color: var(--primary-color);
    border-radius: 50px;
    font-weight: 600;
    font-size: 0.875rem;
    margin-bottom: 1rem;
    border: 1px solid rgba(99, 102, 241, 0.2);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--dark-color);
    font-family: var(--font-heading);
    margin-bottom: 1rem;
}

.section-description {
    font-size: 1.125rem;
    color: var(--gray-medium);
    max-width: 600px;
    margin: 0 auto;
}

/* ==================== 服务区块 ==================== */
.services {
    background: var(--light-color);
}

.services-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.service-card {
    background: var(--white);
    border-radius: 20px;
    padding: 2.5rem;
    box-shadow: var(--shadow-md);
    transition: var(--transition-base);
    position: relative;
    overflow: hidden;
}

.service-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 0;
    background: var(--gradient-primary);
    transition: var(--transition-base);
}

.service-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-xl);
}

.service-card:hover::before {
    height: 100%;
}

.service-card.featured {
    background: var(--gradient-primary);
    color: var(--white);
    transform: scale(1.05);
}

.service-card.featured .service-title,
.service-card.featured .service-description,
.service-card.featured .service-features li {
    color: var(--white);
}

.service-badge {
    position: absolute;
    top: 20px;
    right: 20px;
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
}

.service-icon {
    width: 70px;
    height: 70px;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.1), rgba(139, 92, 246, 0.1));
    border-radius: 15px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
    transition: var(--transition-base);
}

.service-icon img {
    filter: none;
}

.service-card.featured .service-icon {
    background: rgba(255, 255, 255, 0.2);
}

.service-icon i {
    font-size: 2rem;
    color: var(--primary-color);
}

.service-card.featured .service-icon i {
    color: var(--white);
}

.service-card:hover .service-icon {
    transform: rotateY(360deg);
}

.service-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--dark-color);
    margin-bottom: 1rem;
}

.service-description {
    color: var(--gray-medium);
    margin-bottom: 1.5rem;
    line-height: 1.8;
}

.service-features {
    margin-bottom: 1.5rem;
}

.service-features li {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--gray-dark);
    margin-bottom: 0.5rem;
}

.service-features i {
    color: var(--primary-color);
    font-size: 0.875rem;
}

.service-card.featured .service-features i {
    color: var(--white);
}

.service-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--primary-color);
    font-weight: 600;
    transition: var(--transition-base);
}

.service-card.featured .service-link {
    color: var(--white);
}

.service-link:hover {
    gap: 1rem;
}

/* ==================== 优势区块 ==================== */
.advantages {
    background: var(--dark-color);
    color: var(--white);
}

.advantages .section-tag {
    background: rgba(255, 255, 255, 0.1);
    color: var(--white);
    border-color: rgba(255, 255, 255, 0.2);
}

.advantages .section-title {
    color: var(--white);
}

.advantages-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
}

.advantage-item {
    text-align: center;
    padding: 2rem;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 15px;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: var(--transition-base);
}

.advantage-item:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: translateY(-5px);
}

.advantage-number {
    font-size: 3rem;
    font-weight: 700;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 1rem;
}

.advantage-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.advantage-text {
    color: var(--gray-light);
    font-size: 0.9375rem;
}

/* ==================== 案例展示 ==================== */
.cases-filter {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.625rem 1.5rem;
    border: 2px solid var(--gray-light);
    background: transparent;
    color: var(--gray-dark);
    border-radius: 50px;
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition-base);
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--gradient-primary);
    color: var(--white);
    border-color: transparent;
    box-shadow: var(--shadow-glow);
}

.cases-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.case-card {
    background: var(--white);
    border-radius: 15px;
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: var(--transition-base);
}

.case-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-xl);
}

.case-image {
    position: relative;
    height: 250px;
    overflow: hidden;
}

.case-placeholder {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--white);
}

.case-placeholder i {
    font-size: 4rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.case-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(99, 102, 241, 0.9);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: var(--transition-base);
}

.case-card:hover .case-overlay {
    opacity: 1;
}

.case-view {
    width: 50px;
    height: 50px;
    background: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
    font-size: 1.25rem;
    transition: var(--transition-base);
}

.case-view:hover {
    transform: scale(1.1);
}

.case-content {
    padding: 1.5rem;
}

.case-category {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: rgba(99, 102, 241, 0.1);
    color: var(--primary-color);
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.case-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--dark-color);
    margin-bottom: 0.5rem;
}

.case-text {
    color: var(--gray-medium);
    font-size: 0.9375rem;
    line-height: 1.6;
}

/* ==================== 关于我们 ==================== */
.about {
    background: var(--light-color);
}

.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.about-content {
    text-align: left;
}

.about-content .section-header {
    text-align: left;
    margin-bottom: 2rem;
}

.about-text {
    color: var(--gray-medium);
    line-height: 1.8;
    margin-bottom: 1.5rem;
}

.about-stats {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
    margin-top: 2rem;
}

.stat-item {
    text-align: center;
    padding: 1.5rem;
    background: var(--white);
    border-radius: 15px;
    box-shadow: var(--shadow-sm);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.5rem;
}

.stat-label {
    color: var(--gray-medium);
    font-size: 0.9375rem;
}

.about-image {
    height: 500px;
}

.about-image-placeholder {
    width: 100%;
    height: 100%;
    background: var(--gradient-primary);
    border-radius: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--white);
    box-shadow: var(--shadow-xl);
}

.about-image-placeholder i {
    font-size: 5rem;
    margin-bottom: 1rem;
    opacity: 0.8;
}

.about-image-placeholder p {
    font-size: 1.5rem;
    font-weight: 600;
}

/* ==================== 服务流程 ==================== */
.process-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 2rem;
    position: relative;
}

.process-item {
    text-align: center;
    position: relative;
}

.process-icon {
    width: 100px;
    height: 100px;
    background: var(--gradient-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    box-shadow: var(--shadow-glow);
    transition: var(--transition-base);
}

.process-item:hover .process-icon {
    transform: scale(1.1) rotate(360deg);
}

.process-icon i {
    font-size: 2.5rem;
    color: var(--white);
}

.process-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--dark-color);
    margin-bottom: 0.75rem;
}

.process-text {
    color: var(--gray-medium);
    font-size: 0.9375rem;
}

.process-arrow {
    position: absolute;
    top: 50px;
    right: -50%;
    font-size: 2rem;
    color: var(--gray-light);
    display: none;
}

.process-item:not(:last-child) .process-arrow {
    display: block;
}

/* ==================== 新闻资讯 ==================== */
.news {
    background: var(--light-color);
}

.news-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
}

.news-card {
    background: var(--white);
    border-radius: 15px;
    padding: 2rem;
    box-shadow: var(--shadow-md);
    display: flex;
    gap: 1.5rem;
    transition: var(--transition-base);
}

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

.news-date {
    flex-shrink: 0;
    width: 70px;
    height: 70px;
    background: var(--gradient-primary);
    border-radius: 10px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--white);
}

.date-day {
    font-size: 1.75rem;
    font-weight: 700;
    line-height: 1;
}

.date-month {
    font-size: 0.875rem;
}

.news-content {
    flex: 1;
}

.news-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--dark-color);
    margin-bottom: 0.75rem;
    line-height: 1.4;
}

.news-text {
    color: var(--gray-medium);
    font-size: 0.9375rem;
    line-height: 1.6;
    margin-bottom: 1rem;
}

.news-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--primary-color);
    font-weight: 600;
    font-size: 0.9375rem;
    transition: var(--transition-base);
}

.news-link:hover {
    gap: 1rem;
}

/* ==================== 联系我们 ==================== */
.contact {
    background: var(--dark-color);
    color: var(--white);
}

.contact .section-tag {
    background: rgba(255, 255, 255, 0.1);
    color: var(--white);
    border-color: rgba(255, 255, 255, 0.2);
}

.contact .section-title {
    color: var(--white);
}

.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
}

.contact-info .section-header {
    text-align: left;
    margin-bottom: 2rem;
}

.contact-text {
    color: var(--gray-light);
    margin-bottom: 2rem;
    line-height: 1.8;
}

.contact-items {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.contact-item {
    display: flex;
    gap: 1rem;
    align-items: flex-start;
}

.contact-icon {
    width: 50px;
    height: 50px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.contact-icon i {
    font-size: 1.25rem;
    color: var(--primary-light);
}

.contact-details h4 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.contact-details p {
    color: var(--gray-light);
    font-size: 0.9375rem;
}

.contact-form {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 2.5rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-input {
    width: 100%;
    padding: 0.875rem 1.25rem;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 10px;
    color: var(--white);
    font-size: 1rem;
    transition: var(--transition-base);
}

.form-input:focus {
    outline: none;
    background: rgba(255, 255, 255, 0.15);
    border-color: var(--primary-light);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-input::placeholder {
    color: rgba(255, 255, 255, 0.5);
}

.form-input option {
    background: var(--dark-color);
    color: var(--white);
}

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

/* ==================== 页脚 ==================== */
.footer {
    background: var(--gray-dark);
    color: var(--gray-light);
    padding: var(--spacing-lg) 0 var(--spacing-md);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-title {
    color: var(--white);
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
}

.footer-text {
    line-height: 1.8;
    margin-bottom: 1.5rem;
}

.footer-social {
    display: flex;
    gap: 1rem;
}

.social-link {
    width: 40px;
    height: 40px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-base);
}

.social-link:hover {
    background: var(--primary-color);
    transform: translateY(-3px);
}

.footer-links li {
    margin-bottom: 0.75rem;
}

.footer-links a {
    color: var(--gray-light);
    transition: var(--transition-base);
}

.footer-links a:hover {
    color: var(--primary-light);
    padding-left: 5px;
}

.footer-contact li {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.75rem;
}

.footer-contact i {
    color: var(--primary-light);
}

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

.footer-bottom a {
    color: var(--primary-light);
}

.footer-bottom a:hover {
    text-decoration: underline;
}

/* ==================== 返回顶部 ==================== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--gradient-primary);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    box-shadow: var(--shadow-xl);
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-base);
    z-index: 999;
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-glow);
}

/* ==================== 响应式设计 ==================== */
@media screen and (max-width: 1024px) {
    .services-grid,
    .cases-grid,
    .news-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .advantages-grid,
    .process-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .process-arrow {
        display: none !important;
    }
    
    .hero-container,
    .about-grid,
    .contact-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .hero-image {
        display: none;
    }
}

@media screen and (max-width: 768px) {
    :root {
        --spacing-lg: 3rem;
        --spacing-xl: 4rem;
    }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        background: var(--white);
        box-shadow: var(--shadow-lg);
        transition: var(--transition-base);
        padding: 2rem;
    }
    
    .nav-menu.show {
        left: 0;
    }
    
    .nav-list {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-toggle {
        display: block;
    }
    
    .hero-title-main {
        font-size: 2.5rem;
    }
    
    .hero-title-sub {
        font-size: 1.75rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .services-grid,
    .cases-grid,
    .advantages-grid,
    .process-grid,
    .news-grid,
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    .service-card.featured {
        transform: none;
    }
    
    .about-stats {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .hero-buttons {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
}

@media screen and (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero-title-main {
        font-size: 2rem;
    }
    
    .hero-title-sub {
        font-size: 1.5rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
    
    .about-stats {
        grid-template-columns: 1fr;
    }
}