/* ===== Front-end Styles ===== */
:root {
    --primary: #1e3a5f;
    --primary-light: #2c5282;
    --accent: #3182ce;
    --text: #2d3748;
    --text-light: #718096;
    --bg: #ffffff;
    --bg-light: #f7fafc;
    --border: #e2e8f0;
    --shadow: 0 4px 6px -1px rgba(0,0,0,0.1);
    --radius: 8px;
    --container: 1200px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    color: var(--text);
    background: var(--bg);
    line-height: 1.6;
}

.container {
    max-width: var(--container);
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
.site-header {
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}
.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}
.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    text-decoration: none;
    color: var(--primary);
}
.logo-mark {
    width: 40px; height: 40px;
    background: var(--primary);
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    font-weight: 700;
    border-radius: var(--radius);
}
.logo-text strong {
    display: block;
    font-size: 16px;
    line-height: 1.2;
}
.logo-text span {
    font-size: 12px;
    color: var(--text-light);
}

.main-nav {
    display: flex;
    align-items: center;
    gap: 4px;
}
.main-nav a {
    padding: 8px 16px;
    color: var(--text);
    text-decoration: none;
    font-size: 14px;
    border-radius: var(--radius);
    transition: all .2s;
}
.main-nav a:hover,
.main-nav a.active {
    color: var(--accent);
    background: var(--bg-light);
}

.nav-dropdown { position: relative; }
.dropdown-menu {
    position: absolute;
    top: calc(100% + 8px);
    left: 0;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    min-width: 160px;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-4px);
    transition: all .2s;
    padding: 6px 0;
}
.nav-dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}
.dropdown-menu a {
    display: block;
    padding: 8px 16px;
    white-space: nowrap;
}
.dropdown-menu a:hover {
    background: var(--bg-light);
}

.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 24px;
    cursor: pointer;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 10px 24px;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    font-size: 14px;
    text-decoration: none;
    transition: all .2s;
}
.btn-primary {
    background: var(--primary);
    color: #fff;
}
.btn-primary:hover { background: var(--primary-light); }
.btn-outline {
    background: transparent;
    color: var(--primary);
    border: 1px solid var(--primary);
}
.btn-outline:hover { background: var(--primary); color: #fff; }
.btn-lg { padding: 14px 32px; font-size: 16px; }

/* Hero */
.hero {
    background: linear-gradient(135deg, #1a202c 0%, #2c5282 100%);
    color: #fff;
    padding: 100px 20px;
    text-align: center;
}
.hero-content h1 {
    font-size: 42px;
    font-weight: 700;
    margin-bottom: 20px;
    line-height: 1.3;
}
.hero-content p {
    font-size: 18px;
    color: #cbd5e0;
    margin-bottom: 32px;
    line-height: 1.8;
}
.hero-btns {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

/* Sections */
.section { padding: 80px 20px; }
.section-light { background: var(--bg-light); }
.section-header {
    text-align: center;
    margin-bottom: 48px;
}
.section-header h2 {
    font-size: 32px;
    color: var(--primary);
    margin-bottom: 12px;
}
.section-header p {
    color: var(--text-light);
    font-size: 16px;
}

/* Page Header */
.page-header {
    background: var(--primary);
    color: #fff;
    padding: 60px 20px;
    text-align: center;
}
.page-header h1 {
    font-size: 36px;
    margin-bottom: 12px;
}
.page-header p {
    color: #cbd5e0;
    font-size: 16px;
}
.page-header-sm { padding: 40px 20px; }
.page-header-sm h1 { font-size: 28px; }

/* Product Grid */
.product-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(270px, 1fr));
    gap: 24px;
}
.product-card {
    background: var(--bg);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    text-decoration: none;
    color: var(--text);
    transition: transform .2s, box-shadow .2s;
    border: 1px solid var(--border);
}
.product-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
}
.product-image {
    height: 200px;
    background: var(--bg-light);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}
.product-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}
.placeholder-img {
    color: var(--text-light);
    font-size: 14px;
}
.product-info {
    padding: 20px;
}
.product-cat {
    font-size: 12px;
    color: var(--accent);
    margin-bottom: 6px;
    display: block;
}
.product-info h3 {
    font-size: 16px;
    margin-bottom: 8px;
    color: var(--primary);
}
.product-info p {
    font-size: 13px;
    color: var(--text-light);
    line-height: 1.5;
}

/* Article Grid */
.article-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 24px;
}
.article-card {
    background: var(--bg);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    text-decoration: none;
    color: var(--text);
    transition: transform .2s;
    border: 1px solid var(--border);
}
.article-card:hover { transform: translateY(-4px); }
.article-card img {
    width: 100%;
    height: 180px;
    object-fit: cover;
}
.article-card-body {
    padding: 20px;
}
.article-cat {
    font-size: 12px;
    color: var(--accent);
    margin-bottom: 6px;
    display: block;
}
.article-card-body h3 {
    font-size: 16px;
    margin-bottom: 8px;
    color: var(--primary);
}
.article-card-body p {
    font-size: 13px;
    color: var(--text-light);
    margin-bottom: 12px;
    line-height: 1.5;
}
.article-date {
    font-size: 12px;
    color: #a0aec0;
}
.article-meta {
    display: flex;
    gap: 16px;
    font-size: 12px;
    color: #a0aec0;
}

/* Feature Grid */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 24px;
}
.feature-card {
    text-align: center;
    padding: 32px 24px;
    background: var(--bg);
    border-radius: var(--radius);
    border: 1px solid var(--border);
    transition: box-shadow .2s;
}
.feature-card:hover {
    box-shadow: var(--shadow);
}
.feature-icon {
    width: 56px;
    height: 56px;
    background: var(--bg-light);
    color: var(--accent);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    border-radius: 50%;
    margin: 0 auto 16px;
}
.feature-card h3 {
    font-size: 16px;
    margin-bottom: 8px;
}
.feature-card p {
    font-size: 13px;
    color: var(--text-light);
}

/* Filter Bar */
.filter-bar {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
    margin-bottom: 30px;
}
.filter-bar a {
    padding: 8px 18px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 20px;
    text-decoration: none;
    color: var(--text);
    font-size: 13px;
    transition: all .2s;
}
.filter-bar a:hover,
.filter-bar a.active {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

/* Detail Layout */
.detail-layout {
    max-width: 900px;
    margin: 0 auto;
}
.detail-image {
    border-radius: var(--radius);
    overflow: hidden;
    margin-bottom: 30px;
}
.detail-image img {
    width: 100%;
    max-height: 500px;
    object-fit: cover;
}
.detail-body h2 {
    font-size: 22px;
    color: var(--primary);
    margin: 30px 0 16px;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--border);
}
.detail-content {
    font-size: 15px;
    line-height: 1.8;
    color: var(--text);
}
.detail-content p { margin-bottom: 16px; }
.detail-content img { max-width: 100%; border-radius: var(--radius); }

.specs-table {
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
}
.spec-row {
    display: flex;
    border-bottom: 1px solid var(--border);
}
.spec-row:last-child { border-bottom: none; }
.spec-label {
    width: 200px;
    background: var(--bg-light);
    padding: 12px 16px;
    font-weight: 500;
    font-size: 14px;
    flex-shrink: 0;
}
.spec-value {
    padding: 12px 16px;
    font-size: 14px;
}

.article-cover {
    width: 100%;
    max-height: 400px;
    object-fit: cover;
    border-radius: var(--radius);
    margin-bottom: 24px;
}
.article-meta-bar {
    display: flex;
    gap: 20px;
    color: var(--text-light);
    font-size: 13px;
    margin-bottom: 20px;
}

/* Download List */
.download-list { overflow-x: auto; }
.download-list .data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 14px;
}
.download-list .data-table th,
.download-list .data-table td {
    padding: 14px 16px;
    text-align: left;
    border-bottom: 1px solid var(--border);
}
.download-list .data-table th {
    background: var(--bg-light);
    font-weight: 600;
    font-size: 13px;
    color: var(--text-light);
}
.download-list .data-table tr:hover { background: var(--bg-light); }

/* About */
.about-layout {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 48px;
    align-items: start;
}
.about-intro h2 {
    font-size: 24px;
    color: var(--primary);
    margin-bottom: 20px;
}
.about-intro p {
    margin-bottom: 16px;
    line-height: 1.8;
    color: var(--text);
}
.about-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 16px;
}
.about-stat {
    background: var(--bg-light);
    padding: 24px;
    border-radius: var(--radius);
    text-align: center;
}
.about-stat strong {
    display: block;
    font-size: 32px;
    color: var(--accent);
    margin-bottom: 4px;
}
.about-stat span {
    font-size: 13px;
    color: var(--text-light);
}

.timeline {
    position: relative;
    padding-left: 24px;
    border-left: 2px solid var(--border);
}
.timeline-item {
    position: relative;
    padding-bottom: 30px;
}
.timeline-item:last-child { padding-bottom: 0; }
.timeline-year {
    position: absolute;
    left: -38px;
    top: 0;
    width: 28px;
    height: 28px;
    background: var(--primary);
    color: #fff;
    font-size: 11px;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
}
.timeline-content {
    background: var(--bg-light);
    padding: 16px 20px;
    border-radius: var(--radius);
    font-size: 14px;
}

/* Contact */
.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
}
.contact-info h2 {
    font-size: 24px;
    color: var(--primary);
    margin-bottom: 24px;
}
.contact-item {
    margin-bottom: 20px;
}
.contact-item strong {
    display: block;
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 4px;
}
.contact-item p {
    font-size: 15px;
    line-height: 1.6;
}
.map-placeholder {
    background: var(--bg-light);
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    height: 100%;
    min-height: 350px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    gap: 6px;
    margin-top: 40px;
}
.pagination a,
.pagination span {
    padding: 8px 14px;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    text-decoration: none;
    color: var(--text);
    font-size: 14px;
}
.pagination a:hover { background: var(--bg-light); }
.pagination .current {
    background: var(--primary);
    color: #fff;
    border-color: var(--primary);
}

/* Footer */
.site-footer {
    background: #1a202c;
    color: #a0aec0;
    padding: 60px 20px 0;
}
.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 40px;
    margin-bottom: 40px;
}
.footer-grid h4 {
    color: #fff;
    font-size: 16px;
    margin-bottom: 16px;
}
.footer-grid p {
    font-size: 14px;
    line-height: 1.8;
    margin-bottom: 6px;
}
.footer-grid a {
    color: #a0aec0;
    text-decoration: none;
}
.footer-grid a:hover { color: #fff; }
.footer-bottom {
    border-top: 1px solid #2d3748;
    padding: 20px 0;
    text-align: center;
    font-size: 13px;
}

/* Responsive */
@media (max-width: 900px) {
    .main-nav {
        position: fixed;
        top: 70px; left: 0; right: 0;
        background: var(--bg);
        flex-direction: column;
        padding: 16px;
        border-bottom: 1px solid var(--border);
        display: none;
    }
    .main-nav.open { display: flex; }
    .nav-dropdown .dropdown-menu {
        position: static;
        opacity: 1;
        visibility: visible;
        transform: none;
        box-shadow: none;
        border: none;
        padding: 0 0 0 16px;
    }
    .mobile-menu-btn { display: block; }
    .hero-content h1 { font-size: 28px; }
    .about-layout { grid-template-columns: 1fr; }
    .contact-grid { grid-template-columns: 1fr; }
    .footer-grid { grid-template-columns: 1fr; }
    .spec-row { flex-direction: column; }
    .spec-label { width: auto; }
}