/* ===== 基础样式 ===== */
:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --primary-light: #3b82f6;
    --secondary: #0ea5e9;
    --accent: #f59e0b;
    --dark: #0f172a;
    --dark-light: #1e293b;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --white: #ffffff;
    --success: #10b981;
    --gradient: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
    --radius: 12px;
    --radius-lg: 16px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: 'Noto Sans SC', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    color: var(--dark);
    line-height: 1.6;
    background: var(--white);
    overflow-x: hidden;
}

.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 24px;
}

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

ul {
    list-style: none;
}

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

/* ===== 按钮样式 ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 32px;
    border-radius: 50px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    border: 2px solid transparent;
    white-space: nowrap;
}

.btn-primary {
    background: var(--gradient);
    color: var(--white);
    border: none;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(37, 99, 235, 0.3);
}

.btn-outline {
    background: transparent;
    color: var(--white);
    border: 2px solid rgba(255, 255, 255, 0.3);
}

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

.btn-full {
    width: 100%;
}

/* ===== 导航栏 ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.navbar .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 72px;
}

.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 22px;
    font-weight: 700;
    color: var(--dark);
}

.logo-icon {
    font-size: 28px;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 36px;
}

.nav-links a {
    font-size: 15px;
    font-weight: 500;
    color: var(--gray-600);
    transition: var(--transition);
    position: relative;
}

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

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

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

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.mobile-menu-btn span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--dark);
    transition: var(--transition);
}

/* ===== Hero 区域 ===== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--dark);
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background: url('../images/hero_bg.png') center/cover no-repeat;
}

.hero-gradient {
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, rgba(15,23,42,0.85) 0%, rgba(30,27,75,0.85) 50%, rgba(15,23,42,0.85) 100%);
}

.hero-particles {
    position: absolute;
    inset: 0;
    background-image:
        radial-gradient(circle at 20% 50%, rgba(37, 99, 235, 0.15) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(14, 165, 233, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 40% 80%, rgba(245, 158, 11, 0.08) 0%, transparent 50%);
}

.hero-content {
    position: relative;
    z-index: 2;
    text-align: center;
    max-width: 900px;
    padding: 120px 0 80px;
}

.hero-badge {
    display: inline-block;
    padding: 8px 20px;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 50px;
    color: var(--accent);
    font-size: 14px;
    font-weight: 500;
    margin-bottom: 24px;
    backdrop-filter: blur(10px);
}

.hero-title {
    font-size: clamp(36px, 6vw, 72px);
    font-weight: 900;
    line-height: 1.1;
    margin-bottom: 24px;
}

.title-line {
    display: block;
    color: var(--white);
}

.title-line.highlight {
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(16px, 2vw, 20px);
    color: var(--gray-400);
    max-width: 700px;
    margin: 0 auto 40px;
    line-height: 1.7;
}

.hero-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 60px;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 48px;
    flex-wrap: wrap;
}

.stat-item {
    color: var(--white);
    text-align: center;
}

.stat-number {
    font-size: 42px;
    font-weight: 900;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    display: block;
    font-size: 14px;
    color: var(--gray-400);
    margin-top: 4px;
}

.hero-scroll {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    z-index: 2;
}

.hero-scroll a {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: var(--gray-400);
    font-size: 12px;
    transition: var(--transition);
}

.hero-scroll a:hover {
    color: var(--white);
}

.scroll-mouse {
    width: 26px;
    height: 40px;
    border: 2px solid var(--gray-400);
    border-radius: 13px;
    position: relative;
}

.scroll-wheel {
    width: 4px;
    height: 8px;
    background: var(--gray-400);
    border-radius: 2px;
    position: absolute;
    top: 8px;
    left: 50%;
    transform: translateX(-50%);
    animation: scroll 2s ease-in-out infinite;
}

@keyframes scroll {
    0%, 100% { opacity: 1; transform: translateX(-50%) translateY(0); }
    50% { opacity: 0.3; transform: translateX(-50%) translateY(8px); }
}

/* ===== Section 通用 ===== */
.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-tag {
    display: inline-block;
    padding: 6px 16px;
    background: var(--gray-100);
    color: var(--primary);
    border-radius: 50px;
    font-size: 13px;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 16px;
}

.section-title {
    font-size: clamp(28px, 4vw, 44px);
    font-weight: 900;
    margin-bottom: 16px;
    color: var(--dark);
}

.section-desc {
    font-size: 18px;
    color: var(--gray-500);
    max-width: 600px;
    margin: 0 auto;
}

/* ===== 关于我们 ===== */
.about {
    padding: 120px 0;
    background: var(--white);
}

.about-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    margin-bottom: 80px;
}

.about-card {
    padding: 36px 28px;
    background: var(--gray-100);
    border-radius: var(--radius-lg);
    text-align: center;
    transition: var(--transition);
}

.about-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    background: var(--white);
}

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

.about-card h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--dark);
}

.about-card p {
    font-size: 15px;
    color: var(--gray-600);
    line-height: 1.7;
}

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

.story-content h3 {
    font-size: 28px;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--dark);
}

.story-content p {
    font-size: 16px;
    color: var(--gray-600);
    line-height: 1.8;
    margin-bottom: 16px;
}

.story-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 24px;
}

.tag {
    padding: 6px 16px;
    background: var(--gray-100);
    border-radius: 50px;
    font-size: 13px;
    color: var(--gray-600);
    font-weight: 500;
}

.story-image {
    display: flex;
    justify-content: center;
}

.image-placeholder {
    width: 100%;
    max-width: 450px;
    aspect-ratio: 4/3;
    background: var(--gradient);
    border-radius: var(--radius-lg);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--white);
    box-shadow: var(--shadow-xl);
}

.image-text {
    font-size: 36px;
    font-weight: 900;
}

.image-sub {
    font-size: 18px;
    opacity: 0.8;
    margin-top: 8px;
}

/* ===== 产品与服务 ===== */
.products {
    padding: 120px 0;
    background: var(--gray-100);
}

.product-tabs {
    display: flex;
    justify-content: center;
    gap: 12px;
    margin-bottom: 48px;
    flex-wrap: wrap;
}

.tab-btn {
    padding: 10px 24px;
    border: 2px solid var(--gray-200);
    background: var(--white);
    border-radius: 50px;
    font-size: 14px;
    font-weight: 500;
    color: var(--gray-600);
    cursor: pointer;
    transition: var(--transition);
}

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

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

.products-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}

.product-card {
    background: var(--white);
    border-radius: var(--radius-lg);
    padding: 32px;
    position: relative;
    transition: var(--transition);
    border: 1px solid var(--gray-200);
}

.product-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-xl);
    border-color: transparent;
}

.product-card.hidden {
    display: none;
}

.product-badge {
    position: absolute;
    top: 16px;
    right: 16px;
    padding: 4px 12px;
    background: var(--accent);
    color: var(--white);
    border-radius: 50px;
    font-size: 12px;
    font-weight: 600;
}

.product-icon {
    font-size: 48px;
    margin-bottom: 16px;
}

.product-card h3 {
    font-size: 20px;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--dark);
}

.product-desc {
    font-size: 14px;
    color: var(--gray-600);
    line-height: 1.7;
    margin-bottom: 20px;
    display: -webkit-box;
    -webkit-line-clamp: 4;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.product-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 16px;
}

.product-tech span {
    padding: 4px 12px;
    background: var(--gray-100);
    border-radius: 50px;
    font-size: 12px;
    color: var(--gray-500);
    font-weight: 500;
}

.product-links {
    margin-top: 16px;
    padding-top: 16px;
    border-top: 1px solid var(--gray-200);
}

.product-link {
    font-size: 14px;
    font-weight: 600;
    color: var(--primary);
    transition: var(--transition);
}

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

/* ===== 客户案例 ===== */
.cases {
    padding: 120px 0;
    background: var(--white);
}

.cases-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
}

.case-card {
    background: var(--gray-100);
    border-radius: var(--radius-lg);
    padding: 40px 32px;
    position: relative;
    transition: var(--transition);
}

.case-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-xl);
    background: var(--white);
}

.case-number {
    font-size: 64px;
    font-weight: 900;
    color: var(--gray-200);
    line-height: 1;
    margin-bottom: 20px;
}

.case-content h3 {
    font-size: 22px;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--dark);
}

.case-content p {
    font-size: 15px;
    color: var(--gray-600);
    line-height: 1.7;
    margin-bottom: 20px;
}

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

.case-tags span {
    padding: 4px 12px;
    background: var(--primary);
    color: var(--white);
    border-radius: 50px;
    font-size: 12px;
    font-weight: 500;
}

/* ===== 联系我们 ===== */
.contact {
    padding: 120px 0;
    background: var(--gray-100);
}

.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: start;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 28px;
}

.info-item {
    display: flex;
    gap: 16px;
    align-items: flex-start;
}

.info-icon {
    font-size: 32px;
    flex-shrink: 0;
}

.info-content h4 {
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 4px;
    color: var(--dark);
}

.info-content p {
    font-size: 15px;
    color: var(--gray-600);
}

.info-content a {
    color: var(--primary);
    font-weight: 500;
}

.info-content a:hover {
    text-decoration: underline;
}

.contact-form {
    background: var(--white);
    padding: 40px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
}

.form-group {
    margin-bottom: 20px;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 14px 18px;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius);
    font-size: 15px;
    font-family: inherit;
    transition: var(--transition);
    background: var(--gray-100);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary);
    background: var(--white);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

/* ===== 页脚 ===== */
.footer {
    background: var(--dark);
    color: var(--gray-400);
    padding: 80px 0 30px;
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 48px;
    margin-bottom: 60px;
}

.footer-brand .logo {
    color: var(--white);
    margin-bottom: 16px;
}

.footer-desc {
    font-size: 14px;
    line-height: 1.7;
}

.footer-links h4 {
    color: var(--white);
    font-size: 16px;
    font-weight: 700;
    margin-bottom: 20px;
}

.footer-links ul {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-links a {
    font-size: 14px;
    color: var(--gray-400);
    transition: var(--transition);
}

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

.footer-bottom {
    padding-top: 30px;
    border-top: 1px solid var(--dark-light);
    text-align: center;
    font-size: 14px;
}

.footer-bottom a {
    color: var(--gray-400);
    transition: var(--transition);
}

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

/* ===== 回到顶部 ===== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--gradient);
    color: var(--white);
    border: none;
    border-radius: 50%;
    font-size: 20px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
    box-shadow: var(--shadow-lg);
}

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

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 25px rgba(37, 99, 235, 0.4);
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
    .about-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .products-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .footer-content {
        grid-template-columns: 1fr 1fr;
        gap: 32px;
    }
}

@media (max-width: 768px) {
    .nav-links {
        position: fixed;
        top: 72px;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        box-shadow: var(--shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition);
    }
    
    .nav-links.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .mobile-menu-btn {
        display: flex;
    }
    
    .hero-stats {
        gap: 32px;
    }
    
    .about-grid {
        grid-template-columns: 1fr;
    }
    
    .about-story {
        grid-template-columns: 1fr;
        gap: 40px;
    }
    
    .products-grid {
        grid-template-columns: 1fr;
    }
    
    .cases-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: 32px;
    }
    
    .product-tabs {
        gap: 8px;
    }
    
    .tab-btn {
        padding: 8px 16px;
        font-size: 13px;
    }
}

@media (max-width: 480px) {
    .hero-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: 24px;
    }
    
    .contact-form {
        padding: 24px;
    }
}

/* ===== 动画 ===== */
.fade-in {
    opacity: 1;
    transform: translateY(0);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.fade-in-hidden {
    opacity: 0;
    transform: translateY(30px);
}

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