/* ============================================
   北京大千智联科技有限公司 - 官方网站样式
   ============================================ */

/* --- Reset & Base --- */
*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #1A6BFF;
    --primary-dark: #0d4dcc;
    --primary-light: #4d8bff;
    --accent: #1A6BFF;
    --accent-gold: #c9a84c;
    --bg-dark: #060d17;
    --bg-deep: #091420;
    --bg-card: #0d1a2b;
    --bg-card-hover: #112236;
    --text-primary: #e8edf2;
    --text-secondary: #a8b8c8;
    --text-muted: #6b7d90;
    --text-nav: #1a2a4a;
    --text-nav-secondary: #4a5a7a;
    --border: #1a2d42;
    --border-light: #243548;
    --border-soft: #e1e8f0;
    --gradient-hero: linear-gradient(135deg, #060d17 0%, #091420 40%, #0a1a2f 100%);
    --gradient-section: linear-gradient(180deg, #091420 0%, #060d17 100%);
    --gradient-card: linear-gradient(180deg, rgba(13,26,43,0.95) 0%, rgba(9,20,32,0.98) 100%);
    --radius: 12px;
    --radius-lg: 20px;
    --shadow: 0 4px 24px rgba(0,0,0,0.3);
    --shadow-lg: 0 8px 48px rgba(0,0,0,0.4);
    --transition: 0.3s cubic-bezier(0.4,0,0.2,1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
    background: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.7;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
ul, ol { list-style: none; }

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* --- Navigation --- */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 14px 0;
    transition: var(--transition);
    background: #ffffff;
    border-bottom: 1px solid transparent;
}
.nav.scrolled {
    background: #ffffff;
    border-bottom: 1px solid var(--border-soft);
    padding: 8px 0;
    box-shadow: 0 2px 20px rgba(26,42,74,0.06);
}
.nav .container {
    display: flex;
    align-items: center;
    justify-content: space-between;
}
.nav-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 2px 0;
}
.nav-logo-img {
    height: 46px;
    width: auto;
    display: block;
    border-radius: 6px;
}

.nav-links { display: flex; gap: 36px; align-items: center; }
.nav-links a {
    font-size: 14px;
    color: var(--text-nav-secondary);
    transition: var(--transition);
    position: relative;
    padding: 6px 0;
    font-weight: 500;
}
.nav-links a:hover,
.nav-links a.active { color: var(--primary); }
.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary);
    transition: var(--transition);
}
.nav-links a:hover::after,
.nav-links a.active::after { width: 100%; }

.nav-mobile-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}
.nav-mobile-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text-nav);
    margin: 5px 0;
    transition: var(--transition);
}

/* --- Hero --- */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    background: var(--gradient-hero);
    overflow: hidden;
}
.hero::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: 
        radial-gradient(ellipse at 20% 50%, rgba(26,107,255,0.08) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 20%, rgba(10,110,142,0.06) 0%, transparent 50%),
        radial-gradient(ellipse at 50% 80%, rgba(201,168,76,0.04) 0%, transparent 50%);
}
.hero-particles { position: absolute; top: 0; left: 0; width: 100%; height: 100%; pointer-events: none; z-index: 0; }
.hero .container { position: relative; z-index: 1; padding-top: 80px; }
.hero-content { max-width: 720px; }

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 20px;
    background: rgba(26,107,255,0.1);
    border: 1px solid rgba(26,107,255,0.25);
    border-radius: 50px;
    font-size: 13px;
    color: var(--accent);
    margin-bottom: 32px;
    animation: fadeInUp 0.6s ease-out;
}
.hero-badge::before {
    content: '';
    width: 8px; height: 8px;
    background: var(--accent);
    border-radius: 50%;
    animation: pulse 2s infinite;
}

.hero h1 { 
    font-size: 52px; 
    font-weight: 800; 
    line-height: 1.25; 
    color: #fff; 
    margin-bottom: 8px;
    animation: fadeInUp 0.6s ease-out 0.1s both;
}
.hero h1 em {
    font-style: normal;
    color: var(--accent);
}
.hero h2 {
    font-size: 18px;
    font-weight: 400;
    color: var(--text-secondary);
    margin-bottom: 36px;
    line-height: 1.8;
    animation: fadeInUp 0.6s ease-out 0.2s both;
}

.hero-stats {
    display: flex;
    gap: 48px;
    margin-bottom: 40px;
    animation: fadeInUp 0.6s ease-out 0.3s both;
}
.hero-stat { text-align: center; }
.hero-stat-num { font-size: 32px; font-weight: 800; color: var(--accent); display: block; }
.hero-stat-label { font-size: 13px; color: var(--text-muted); margin-top: 4px; }

.hero-cta {
    display: flex;
    gap: 16px;
    animation: fadeInUp 0.6s ease-out 0.4s both;
}
.btn { 
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 32px; 
    border-radius: 50px; 
    font-size: 15px; 
    font-weight: 600; 
    transition: var(--transition);
    cursor: pointer;
    border: none;
}
.btn-primary {
    background: linear-gradient(135deg, var(--accent), var(--primary-dark));
    color: #fff;
    box-shadow: 0 4px 20px rgba(26,107,255,0.3);
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(26,107,255,0.45);
}
.btn-outline {
    background: transparent;
    color: var(--text-primary);
    border: 1px solid var(--border-light);
}
.btn-outline:hover {
    border-color: var(--accent);
    color: var(--accent);
    transform: translateY(-2px);
}

.hero-visual {
    position: absolute;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 45%;
    z-index: 0;
    opacity: 0.6;
    pointer-events: none;
}
.hero-globe {
    width: 100%;
    aspect-ratio: 1;
    border-radius: 50%;
    background: radial-gradient(circle at 35% 35%, rgba(26,107,255,0.15), transparent 60%);
    position: relative;
}
.hero-globe::before {
    content: '';
    position: absolute;
    inset: 15%;
    border-radius: 50%;
    border: 1px solid rgba(26,107,255,0.12);
    animation: rotate 60s linear infinite;
}
.hero-globe::after {
    content: '';
    position: absolute;
    inset: 30%;
    border-radius: 50%;
    border: 1px solid rgba(201,168,76,0.08);
    animation: rotate 40s linear infinite reverse;
}

/* --- Sections --- */
.section {
    padding: 100px 0;
    position: relative;
}
.section-dark { background: var(--bg-deep); }
.section-darker { background: var(--bg-dark); }

.section-header {
    text-align: center;
    margin-bottom: 64px;
}
.section-tag {
    display: inline-block;
    font-size: 12px;
    font-weight: 600;
    color: var(--accent);
    text-transform: uppercase;
    letter-spacing: 4px;
    margin-bottom: 16px;
}
.section-title {
    font-size: 36px;
    font-weight: 800;
    color: #fff;
    margin-bottom: 16px;
    line-height: 1.3;
}
.section-title em {
    font-style: normal;
    color: var(--accent);
}
.section-desc {
    font-size: 16px;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
    line-height: 1.8;
}

/* --- About --- */
.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 64px;
    align-items: center;
}
.about-image {
    position: relative;
}
.about-image-main {
    width: 100%;
    border-radius: var(--radius-lg);
    background: var(--gradient-card);
    border: 1px solid var(--border);
    padding: 48px;
    position: relative;
    overflow: hidden;
}
.about-image-main::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: 
        radial-gradient(circle at 20% 30%, rgba(26,107,255,0.06) 0%, transparent 50%),
        radial-gradient(circle at 80% 70%, rgba(201,168,76,0.04) 0%, transparent 50%);
}
.about-icon-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
    position: relative;
    z-index: 1;
}
.about-icon-item {
    text-align: center;
    padding: 24px 16px;
    background: rgba(255,255,255,0.03);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    transition: var(--transition);
}
.about-icon-item:hover {
    background: rgba(26,107,255,0.05);
    border-color: rgba(26,107,255,0.2);
    transform: translateY(-2px);
}
.about-icon-num { font-size: 28px; font-weight: 800; color: var(--accent); }
.about-icon-label { font-size: 13px; color: var(--text-muted); margin-top: 8px; }

.about-text h3 { font-size: 24px; font-weight: 700; color: #fff; margin-bottom: 20px; }
.about-text p { color: var(--text-secondary); margin-bottom: 16px; line-height: 1.9; font-size: 15px; }
.about-features { display: flex; flex-direction: column; gap: 12px; margin-top: 24px; }
.about-feature { 
    display: flex; 
    align-items: flex-start; 
    gap: 12px; 
    padding: 14px 18px;
    background: var(--bg-card);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    transition: var(--transition);
}
.about-feature:hover { border-color: var(--border-light); background: var(--bg-card-hover); }
.about-feature-icon {
    width: 36px; height: 36px;
    flex-shrink: 0;
    background: rgba(26,107,255,0.1);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 16px;
    color: var(--accent);
}
.about-feature-text h4 { font-size: 14px; font-weight: 600; color: #fff; }
.about-feature-text p { font-size: 13px; color: var(--text-muted); margin: 2px 0 0; }

/* --- Business --- */
.business-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}
.business-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 40px 32px;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}
.business-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--accent), var(--primary));
    opacity: 0;
    transition: var(--transition);
}
.business-card:hover { 
    border-color: var(--border-light);
    background: var(--bg-card-hover);
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}
.business-card:hover::before { opacity: 1; }
.business-card-icon {
    width: 56px; height: 56px;
    background: rgba(26,107,255,0.08);
    border-radius: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 24px;
    font-size: 26px;
}
.business-card h3 { font-size: 20px; font-weight: 700; color: #fff; margin-bottom: 12px; }
.business-card p { font-size: 14px; color: var(--text-secondary); line-height: 1.8; }
.business-card-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 20px;
}
.business-card-tag {
    font-size: 11px;
    padding: 4px 12px;
    border-radius: 50px;
    background: rgba(26,107,255,0.08);
    color: var(--accent);
    border: 1px solid rgba(26,107,255,0.15);
}

/* --- Products --- */
.products-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 20px;
}
.product-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 32px 24px;
    transition: var(--transition);
    text-align: center;
}
.product-card:hover {
    border-color: var(--accent);
    transform: translateY(-4px);
    box-shadow: 0 8px 32px rgba(26,107,255,0.15);
}
.product-card-icon {
    width: 60px; height: 60px;
    margin: 0 auto 20px;
    background: rgba(26,107,255,0.08);
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 28px;
}
.product-card h3 { font-size: 16px; font-weight: 700; color: #fff; margin-bottom: 10px; }
.product-card p { font-size: 13px; color: var(--text-muted); line-height: 1.7; }

/* --- Tech Platform --- */
.tech-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    align-items: center;
}
.tech-visual {
    position: relative;
    padding: 40px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
}
.tech-layer { margin-bottom: 16px; }
.tech-layer:last-child { margin-bottom: 0; }
.tech-layer-item {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 16px 20px;
    background: rgba(255,255,255,0.02);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    transition: var(--transition);
}
.tech-layer-item:hover { 
    border-color: rgba(26,107,255,0.2); 
    background: rgba(26,107,255,0.03);
}
.tech-layer-dot {
    width: 10px; height: 10px;
    border-radius: 50%;
    background: var(--accent);
    flex-shrink: 0;
}
.tech-layer-item h4 { font-size: 14px; font-weight: 600; color: #fff; flex: 1; }
.tech-layer-item span { font-size: 12px; color: var(--text-muted); }

.tech-text h3 { font-size: 24px; font-weight: 700; color: #fff; margin-bottom: 20px; }
.tech-text p { color: var(--text-secondary); margin-bottom: 14px; line-height: 1.9; font-size: 15px; }
.tech-highlights { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 24px; }
.tech-highlight {
    padding: 16px;
    background: var(--bg-card);
    border-radius: var(--radius);
    border: 1px solid var(--border);
}
.tech-highlight-num { font-size: 20px; font-weight: 800; color: var(--accent); }
.tech-highlight-label { font-size: 12px; color: var(--text-muted); margin-top: 4px; }

/* --- Service --- */
.service-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 16px; }
.service-step {
    text-align: center;
    padding: 32px 16px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    transition: var(--transition);
    position: relative;
}
.service-step:hover { 
    border-color: var(--accent);
    background: var(--bg-card-hover);
    transform: translateY(-2px);
}
.service-step-num {
    width: 40px; height: 40px;
    margin: 0 auto 16px;
    background: linear-gradient(135deg, var(--accent), var(--primary));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 16px;
    font-weight: 800;
    color: #fff;
}
.service-step h4 { font-size: 14px; font-weight: 600; color: #fff; margin-bottom: 8px; }
.service-step p { font-size: 12px; color: var(--text-muted); line-height: 1.6; }

/* --- Footer --- */
.footer {
    background: var(--bg-deep);
    border-top: 1px solid var(--border);
    padding: 60px 0 30px;
}
.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1.2fr;
    gap: 48px;
    margin-bottom: 40px;
}
.footer-brand h3 { font-size: 22px; font-weight: 700; color: #fff; margin-bottom: 12px; }
.footer-brand p { font-size: 13px; color: var(--text-muted); line-height: 1.8; }
.footer-col h4 { font-size: 14px; font-weight: 600; color: #fff; margin-bottom: 20px; }
.footer-col a { display: block; font-size: 13px; color: var(--text-muted); margin-bottom: 12px; transition: var(--transition); }
.footer-col a:hover { color: var(--accent); }
.footer-contact-item { display: flex; gap: 10px; align-items: flex-start; margin-bottom: 14px; }
.footer-contact-item .label { font-size: 12px; color: var(--text-muted); min-width: 48px; }
.footer-contact-item .value { font-size: 13px; color: var(--text-secondary); }
.footer-bottom {
    text-align: center;
    padding-top: 24px;
    border-top: 1px solid var(--border);
}
.footer-bottom p { font-size: 12px; color: var(--text-muted); }
.footer-beian {
    margin-top: 10px;
    justify-content: center;
    gap: 8px;
    font-size: 12px;
    color: var(--text-muted);
}
.footer-beian a {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--text-muted);
    transition: var(--transition);
}
.footer-beian a:hover { color: var(--text-secondary); }
.beian-icon {
    height: 18px;
    width: auto;
    display: inline-block;
}

/* --- Animations --- */
@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(30px); }
    to { opacity: 1; transform: translateY(0); }
}
@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.4; }
}
@keyframes rotate {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}
@keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-20px); }
}

/* Scroll reveal */
.reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}
.reveal.visible { opacity: 1; transform: translateY(0); }

/* --- Responsive --- */
@media (max-width: 1024px) {
    .products-grid { grid-template-columns: repeat(2, 1fr); }
    .hero h1 { font-size: 38px; }
    .hero-visual { display: none; }
}

@media (max-width: 768px) {
    .nav-links { display: none; }
    .nav-links.open {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: #ffffff;
        padding: 24px;
        gap: 20px;
        border-bottom: 1px solid var(--border-soft);
    }
    .nav-links.open a { color: var(--text-nav-secondary); }
    .nav-mobile-toggle { display: block; }
    
    .hero { min-height: auto; padding: 160px 0 80px; }
    .hero h1 { font-size: 30px; }
    .hero h2 { font-size: 15px; }
    .hero-stats { gap: 24px; flex-wrap: wrap; }
    
    .about-grid, .tech-grid { grid-template-columns: 1fr; }
    .business-grid { grid-template-columns: 1fr; }
    .products-grid { grid-template-columns: 1fr; }
    .service-grid { grid-template-columns: repeat(2, 1fr); }
    .footer-grid { grid-template-columns: 1fr 1fr; }
    
    .section { padding: 60px 0; }
    .section-title { font-size: 28px; }
}

@media (max-width: 480px) {
    .hero-stats { flex-direction: column; gap: 16px; }
    .hero-cta { flex-direction: column; }
    .service-grid { grid-template-columns: 1fr; }
    .footer-grid { grid-template-columns: 1fr; }
}