/* 全局样式和变量 */
:root {
    --primary-color: #2E80FF;
    --primary-dark: #1E60D1;
    --secondary-color: #5D9BFF;
    --accent-color: #FF7D00;
    --dark-color: #1F2937;
    --light-color: #F9FAFB;
    --text-color: #374151;
    --text-light: #6B7280;
    --border-color: #E5E7EB;
    --success-color: #10B981;
    --warning-color: #F59E0B;
    --danger-color: #EF4444;
    --transition: all 0.3s ease;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--light-color);
    overflow-x: hidden;
}

/* 容器 */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 头部导航 */
.header {
    background-color: white;
    box-shadow: var(--shadow-sm);
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    transition: var(--transition);
}

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

.header.mobile-menu-open {
    background-color: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
}

.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 0;
}

.navbar-brand .logo {
    height: 40px;
    width: auto;
}

.nav-list {
    display: flex;
    list-style: none;
    gap: 36px;
    align-items: center;
    margin-right: 24px;
}

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

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: var(--transition);
}

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

.nav-actions {
    display: flex;
    gap: 12px;
    align-items: center;
}

/* 按钮样式 */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 20px;
    border: none;
    border-radius: var(--radius-md);
    font-size: 14px;
    font-weight: 500;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    gap: 8px;
}

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

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

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

.btn-outline:hover {
    background-color: var(--primary-color);
    color: white;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-lg {
    padding: 14px 32px;
    font-size: 16px;
}

/* 移动端导航切换按钮 */
.navbar-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.navbar-toggle:hover {
    background-color: var(--light-color);
}

.toggle-bar {
    width: 24px;
    height: 3px;
    background-color: var(--dark-color);
    border-radius: 2px;
    transition: var(--transition);
}

.navbar-toggle.active .toggle-bar:nth-child(1) {
    transform: rotate(45deg) translate(6px, 6px);
}

.navbar-toggle.active .toggle-bar:nth-child(2) {
    opacity: 0;
}

.navbar-toggle.active .toggle-bar:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
}

/* 英雄区域 */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 140px 0 80px;
    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 width="100" height="100" viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg"><rect width="100" height="100" fill="none"/><path d="M0 0 L100 0 L100 100 L0 100 Z" fill="none" stroke="rgba(255,255,255,0.1)" stroke-width="0.5"/><path d="M50 0 L50 100 M0 50 L100 50" stroke="rgba(255,255,255,0.1)" stroke-width="0.5"/></svg>');
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 800px;
    margin: 0 auto;
}

.hero-title {
    font-size: 48px;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 16px;
}

.hero-subtitle {
    font-size: 20px;
    margin-bottom: 40px;
    opacity: 0.9;
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    gap: 24px;
    margin-top: 60px;
    padding-top: 32px;
    border-top: 1px solid rgba(255, 255, 255, 0.2);
}

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

.stat-number {
    display: block;
    font-size: 24px;
    font-weight: 700;
    margin-bottom: 4px;
}

.stat-label {
    font-size: 14px;
    opacity: 0.8;
}

/* 通用区块样式 */
.section {
    padding: 100px 0;
}

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

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

.section-description {
    font-size: 18px;
    color: var(--text-light);
    max-width: 700px;
    margin: 0 auto;
}

/* AI机器人功能区块 */
.ai-robot {
    background-color: white;
}

.robot-features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 32px;
    margin-top: 40px;
}

.robot-feature-item {
    text-align: center;
    padding: 32px;
    background-color: var(--light-color);
    border-radius: var(--radius-xl);
    transition: var(--transition);
}

.robot-feature-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    background-color: white;
}

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

.feature-title {
    font-size: 20px;
    font-weight: 600;
    color: var(--dark-color);
}

/* 关键功能优势区块 */
.key-advantages {
    background-color: var(--light-color);
}

.advantages-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
    margin-top: 40px;
}

.advantage-item {
    padding: 32px;
    background-color: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
}

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

.advantage-icon {
    margin-bottom: 20px;
}

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

.advantage-description {
    color: var(--text-light);
    line-height: 1.6;
}

.advantages-action {
    text-align: center;
    margin-top: 40px;
}

/* 为什么选择美洽区块 */
.why-choose {
    background-color: white;
}

.choose-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.choose-text {
    max-width: 500px;
    margin: 0 auto;
}

.choose-description {
    font-size: 18px;
    line-height: 1.8;
    color: var(--text-color);
}

.choose-features {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.choose-feature-item {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    padding: 20px;
    background-color: var(--light-color);
    border-radius: var(--radius-lg);
    transition: var(--transition);
}

.choose-feature-item:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-md);
}

.choose-feature-item .feature-content {
    flex: 1;
}

.choose-feature-item .feature-title {
    font-size: 18px;
    margin-bottom: 8px;
}

.choose-feature-item .feature-description {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.6;
}

/* 用户评价区块 */
.testimonials {
    background-color: var(--light-color);
}

.testimonials-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 32px;
    margin-top: 40px;
}

.testimonial-item {
    padding: 36px;
    background-color: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
}

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

.testimonial-content {
    font-size: 16px;
    line-height: 1.8;
    color: var(--text-color);
    margin-bottom: 24px;
    font-style: italic;
}

.testimonial-author {
    display: flex;
    align-items: center;
    gap: 12px;
}

.author-info {
    display: flex;
    flex-direction: column;
}

.author-name {
    font-weight: 600;
    color: var(--dark-color);
}

.author-title {
    font-size: 14px;
    color: var(--text-light);
}

/* 新闻报道区块 */
.news {
    background-color: white;
}

.news-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    margin-top: 40px;
}

.news-item {
    padding: 24px;
    background-color: var(--light-color);
    border-radius: var(--radius-lg);
    transition: var(--transition);
}

.news-item:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
    background-color: white;
}

.news-link {
    text-decoration: none;
    color: inherit;
}

.news-title {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--dark-color);
    transition: var(--transition);
}

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

.news-excerpt {
    font-size: 14px;
    color: var(--text-light);
    line-height: 1.6;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

/* 下载区域 */
.download {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-align: center;
}

.download .section-title {
    color: white;
}

.download .section-description {
    color: rgba(255, 255, 255, 0.9);
}

.download-content {
    max-width: 800px;
    margin: 0 auto;
}

.download-buttons {
    display: flex;
    justify-content: center;
    gap: 24px;
    margin-top: 40px;
    flex-wrap: wrap;
}

.btn-download {
    background-color: rgba(255, 255, 255, 0.15);
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(10px);
    padding: 20px;
    width: 280px;
    justify-content: flex-start;
    transition: var(--transition);
}

.btn-download:hover {
    background-color: rgba(255, 255, 255, 0.25);
    border-color: rgba(255, 255, 255, 0.6);
    transform: translateY(-5px);
}

.download-icon {
    font-size: 32px;
    margin-right: 16px;
}

.download-info {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
}

.download-name {
    font-size: 18px;
    font-weight: 600;
    margin-bottom: 4px;
}

.download-version {
    font-size: 14px;
    opacity: 0.8;
}

/* 页脚 */
.footer {
    background-color: var(--dark-color);
    color: white;
    padding: 80px 0 40px;
}

.footer-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr 1fr;
    gap: 50px;
    margin-bottom: 40px;
    padding-bottom: 30px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-brand {
    max-width: 400px;
}

.footer-logo {
    height: 40px;
    width: auto;
    margin-bottom: 15px;
}

.footer-description {
    color: white;
    margin-bottom: 0;
    font-size: 1rem;
    line-height: 1.6;
    opacity: 0.9;
}

.footer-column-title {
    color: var(--primary-color);
    margin-bottom: 20px;
    font-size: 1.2rem;
    font-weight: 600;
    letter-spacing: 0.5px;
}

.footer-nav {
    list-style: none;
}

.footer-nav-item {
    margin-bottom: 15px;
}

.footer-nav-link {
    color: white;
    text-decoration: none;
    transition: var(--transition);
    font-size: 1rem;
    opacity: 0.9;
}

.footer-nav-link:hover {
    opacity: 1;
    color: white;
    text-decoration: underline;
}

.footer-bottom {
    text-align: center;
    padding-top: 20px;
}

.footer-copyright {
    color: rgba(255, 255, 255, 0.7);
    font-size: 14px;
}

/* 回到顶部按钮 */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 24px;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    box-shadow: var(--shadow-lg);
    z-index: 999;
}

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

.back-to-top:hover {
    background-color: #1E60D1;
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
}

/* 响应式设计 */
@media (max-width: 1024px) {
    .hero-title {
        font-size: 36px;
    }
    
    .hero-subtitle {
        font-size: 18px;
    }
    
    .choose-content {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .choose-features {
        order: -1;
    }
    
    .section-title {
        font-size: 28px;
    }
    
    .section-description {
        font-size: 16px;
    }
}

@media (max-width: 768px) {
    /* 移动端导航 */
    .navbar-toggle {
        display: flex;
    }
    
    .navbar-menu {
        position: fixed;
        top: 76px;
        left: 0;
        right: 0;
        background-color: rgba(255, 255, 255, 0.95);
        backdrop-filter: blur(10px);
        box-shadow: var(--shadow-md);
        max-height: 0;
        overflow: hidden;
        transition: var(--transition);
        z-index: 999;
    }
    
    .navbar-menu.open {
        max-height: 500px;
        padding: 20px 0;
    }
    
    .nav-list {
        flex-direction: column;
        gap: 16px;
        align-items: center;
        margin-right: 0;
    }
    
    .nav-actions {
        flex-direction: column;
        gap: 16px;
        margin-top: 16px;
    }
    
    /* 英雄区域 */
    .hero {
        padding: 120px 0 60px;
    }
    
    .hero-title {
        font-size: 28px;
    }
    
    .hero-subtitle {
        font-size: 16px;
    }
    
    .hero-stats {
        grid-template-columns: repeat(2, 1fr);
        gap: 16px;
    }
    
    /* 通用区块 */
    .section {
        padding: 60px 0;
    }
    
    .robot-features, .advantages-grid, .testimonials-grid, .news-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }
    
    .section-title {
        font-size: 24px;
    }
    
    /* 页脚 */
    .footer-content {
        grid-template-columns: 1fr;
        gap: 32px;
        text-align: center;
    }
    
    .footer-brand {
        max-width: 100%;
        margin: 0 auto;
    }
    
    /* 下载按钮 */
    .download-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .btn-download {
        width: 100%;
        max-width: 300px;
        justify-content: center;
    }
    
    /* 为什么选择美洽 */
    .choose-description {
        font-size: 16px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero-title {
        font-size: 24px;
    }
    
    .section-title {
        font-size: 20px;
    }
    
    .advantage-item, .testimonial-item, .robot-feature-item {
        padding: 24px;
    }
    
    .btn-lg {
        padding: 12px 24px;
        font-size: 14px;
    }
}

/* 页面滚动行为 */
html {
    scroll-behavior: smooth;
}

/* 禁止页面滚动的类 */
.no-scroll {
    overflow: hidden;
}

/* 加载动画 */
@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;
}

/* 渐变动画 */
@keyframes gradientShift {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

.hero, .download {
    background-size: 200% 200%;
    animation: gradientShift 8s ease infinite;
}

/* 按钮点击效果 */
.btn {
    position: relative;
    overflow: hidden;
}

.btn::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.3);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.btn:active::after {
    width: 300px;
    height: 300px;
}