:root {
    --primary-deep: #060e1f;
    --primary: #0f1f3d;
    --primary-light: #1a3558;
    --accent-gold: #c8963e;
    --accent-gold-light: #d4a853;
    --accent-gold-pale: #f5ecd7;
    --white: #ffffff;
    --off-white: #f8f9fb;
    --light-gray: #eef0f4;
    --mid-gray: #d1d5db;
    --text-dark: #1a1d24;
    --text-body: #3a3f4a;
    --text-light: #6b7280;
    --text-muted: #9ca3af;
    --shadow-sm: 0 1px 3px rgba(6, 14, 31, 0.04);
    --shadow-md: 0 4px 16px rgba(6, 14, 31, 0.06);
    --shadow-lg: 0 12px 40px rgba(6, 14, 31, 0.10);
    --shadow-gold: 0 8px 32px rgba(200, 150, 62, 0.20);
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --radius-2xl: 28px;
    --transition-fast: 0.2s ease;
    --transition-smooth: 0.35s ease;
    --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
    --font-display: 'Playfair Display', Georgia, serif;
    --max-width: 1100px;
    --nav-height: 72px;
}

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

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

body {
    font-family: var(--font-sans);
    color: var(--text-body);
    background-color: var(--off-white);
    line-height: 1.7;
    min-height: 100vh;
}

::selection {
    background-color: var(--accent-gold);
    color: var(--white);
}

/* NAVIGATION */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 0 2rem;
    height: var(--nav-height);
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: transparent;
    transition: all var(--transition-smooth);
}

.navbar.scrolled {
    background: rgba(255, 255, 255, 0.97);
    backdrop-filter: blur(24px);
    box-shadow: 0 2px 24px rgba(6, 14, 31, 0.08);
}

.navbar .logo {
    display: flex;
    align-items: center;
    text-decoration: none;
    position: relative;
}

.logo-img {
    height: 40px;
    width: auto;
    object-fit: contain;
    transition: opacity var(--transition-smooth);
}

/* 深色导航栏（默认/未滚动）显示 logo2.png */
.logo-dark {
    display: block;
    opacity: 1;
}

/* 浅色导航栏（滚动后）显示 logo.png */
.logo-light {
    display: block;
    opacity: 1;
    position: absolute;
    top: 0;
    left: 0;
    opacity: 0;
    pointer-events: none;
}

.navbar.scrolled .logo-dark {
    opacity: 0;
    pointer-events: none;
}

.navbar.scrolled .logo-light {
    opacity: 1;
    pointer-events: auto;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-links a {
    text-decoration: none;
    color: rgba(255, 255, 255, 0.85);
    font-weight: 500;
    font-size: 0.92rem;
    transition: color var(--transition-fast);
}

.navbar.scrolled .nav-links a {
    color: var(--text-dark);
}

.nav-links a:hover {
    color: var(--accent-gold-light) !important;
}

.navbar.scrolled .nav-links a:hover {
    color: var(--accent-gold) !important;
}

.nav-links a.active {
    color: var(--accent-gold-light) !important;
}

.navbar.scrolled .nav-links a.active {
    color: var(--accent-gold) !important;
}

.nav-cta {
    padding: 9px 20px;
    background: var(--accent-gold);
    color: var(--white) !important;
    border-radius: 50px;
    font-weight: 600;
    font-size: 0.88rem;
    text-decoration: none;
    transition: all var(--transition-smooth);
}

.nav-cta:hover {
    background: var(--accent-gold-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-gold);
}

/* PAGE HEADER */
.page-header {
    background: linear-gradient(170deg, #040b1a 0%, #060e1f 25%, #0a1628 50%, #0f1f3d 75%, #0d1a35 100%);
    padding: 7rem 2rem 4rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.page-header::before {
    content: '';
    position: absolute;
    inset: 0;
    pointer-events: none;
    opacity: 0.03;
    background-image: radial-gradient(circle at 20% 30%, #fff 1px, transparent 1px),
        radial-gradient(circle at 75% 60%, #fff 0.8px, transparent 0.8px);
    background-size: 60px 60px, 80px 80px;
}

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

.page-header-breadcrumb {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    font-size: 0.84rem;
    color: rgba(255, 255, 255, 0.4);
    margin-bottom: 1.2rem;
}

.page-header-breadcrumb a {
    color: rgba(255, 255, 255, 0.5);
    text-decoration: none;
}

.page-header-breadcrumb a:hover {
    color: var(--accent-gold-light);
}

.page-header-breadcrumb .current {
    color: var(--accent-gold-light);
    font-weight: 500;
}

.page-header-category {
    display: inline-block;
    padding: 5px 14px;
    border-radius: 50px;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    margin-bottom: 1.2rem;
    background: rgba(255, 255, 255, 0.05);
    color: var(--accent-gold-light);
    border: 1px solid rgba(255, 255, 255, 0.12);
}

.page-header h1 {
    font-family: var(--font-display);
    font-size: clamp(1.8rem, 4vw, 2.6rem);
    font-weight: 700;
    color: var(--white);
    line-height: 1.2;
    margin-bottom: 0.6rem;
}

.page-header h1 .gold-text {
    color: var(--accent-gold-light);
}

.page-header .model-name {
    font-size: 1rem;
    color: var(--accent-gold-light);
    font-weight: 500;
    margin-bottom: 0.8rem;
}

.page-header .intro-text {
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.55);
    max-width: 600px;
    margin: 0 auto;
    line-height: 1.7;
}

/* MAIN CONTENT */
.main-content {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 2.5rem 2rem 5rem;
}

.article-body {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 3rem;
    align-items: start;
}

.article-main h2 {
    font-family: var(--font-display);
    font-size: 1.45rem;
    font-weight: 700;
    color: var(--primary-deep);
    margin: 2rem 0 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--light-gray);
}

.article-main h2:first-child {
    margin-top: 0;
}

.article-main p {
    font-size: 0.95rem;
    color: var(--text-body);
    margin-bottom: 1rem;
    line-height: 1.8;
}

.article-main ul {
    margin: 0.8rem 0 1.2rem 1.2rem;
}

.article-main ul li {
    font-size: 0.93rem;
    color: var(--text-body);
    margin-bottom: 0.45rem;
    line-height: 1.7;
}

.article-main ul li::marker {
    color: var(--accent-gold);
}

.spec-table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.2rem 0 1.8rem;
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

.spec-table tr {
    border-bottom: 1px solid var(--light-gray);
}

.spec-table tr:last-child {
    border-bottom: none;
}

.spec-table td {
    padding: 0.85rem 1.2rem;
    font-size: 0.88rem;
    color: var(--text-body);
}

.spec-table td:first-child {
    font-weight: 600;
    color: var(--primary-deep);
    background: var(--off-white);
    width: 190px;
    white-space: nowrap;
}

.spec-table td:last-child {
    background: var(--white);
}

/* SIDEBAR */
.article-sidebar {
    position: sticky;
    top: calc(var(--nav-height) + 30px);
}

.sidebar-card {
    background: var(--white);
    border-radius: var(--radius-xl);
    padding: 1.6rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--light-gray);
    margin-bottom: 1.2rem;
}

.sidebar-card h4 {
    font-family: var(--font-display);
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--primary-deep);
    margin-bottom: 1.2rem;
    text-align: center;
}

.sidebar-email {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 1rem;
    background: var(--off-white);
    border-radius: var(--radius-md);
    margin-bottom: 1.2rem;
    transition: all var(--transition-smooth);
    text-decoration: none;
    color: inherit;
}

.sidebar-email:hover {
    background: var(--accent-gold-pale);
}

.sidebar-email .email-icon {
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: var(--accent-gold-pale);
    color: var(--accent-gold);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    flex-shrink: 0;
}

.sidebar-email .email-info {
    min-width: 0;
}

.sidebar-email .email-label {
    font-size: 0.7rem;
    color: var(--text-muted);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    margin-bottom: 2px;
}

.sidebar-email .email-address {
    font-size: 0.82rem;
    color: var(--text-dark);
    font-weight: 600;
    word-break: break-all;
    text-decoration: none;
}

.sidebar-email .email-address:hover {
    color: var(--accent-gold);
}

.sidebar-cta {
    display: block;
    width: 100%;
    padding: 12px;
    background: var(--accent-gold);
    color: var(--white);
    border: none;
    border-radius: 50px;
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    text-align: center;
    text-decoration: none;
    transition: all var(--transition-smooth);
    font-family: var(--font-sans);
}

.sidebar-cta:hover {
    background: var(--accent-gold-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-gold);
}

.sidebar-note {
    text-align: center;
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.8rem;
    line-height: 1.5;
}

/* RELATED */
.related-section {
    margin-top: 4rem;
}

.related-section h3 {
    font-family: var(--font-display);
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--primary-deep);
    margin-bottom: 1.5rem;
    text-align: center;
}

.related-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.2rem;
}

.related-card {
    background: var(--white);
    border-radius: var(--radius-lg);
    padding: 1.4rem;
    box-shadow: var(--shadow-sm);
    text-decoration: none;
    color: inherit;
    transition: all var(--transition-smooth);
    border: 1px solid transparent;
    display: flex;
    flex-direction: column;
}

.related-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(200, 150, 62, 0.2);
}

.related-card .rel-cat {
    font-size: 0.63rem;
    padding: 3px 10px;
    border-radius: 50px;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    display: inline-block;
    margin-bottom: 0.8rem;
    width: fit-content;
}

.rel-cat-chemical {
    background: #fef3e4;
    color: #d97706;
}

.rel-cat-materials {
    background: #eef2ff;
    color: #4f46e5;
}

.rel-cat-biomedical {
    background: #ecfdf5;
    color: #059669;
}

.related-card h5 {
    font-size: 0.92rem;
    font-weight: 700;
    color: var(--primary-deep);
    margin-bottom: 0.25rem;
}

.related-card .rel-model {
    font-size: 0.73rem;
    color: var(--accent-gold);
    font-weight: 500;
    text-transform: uppercase;
}

.related-card .rel-arrow {
    margin-top: auto;
    padding-top: 0.8rem;
    color: var(--accent-gold);
    font-weight: 600;
    font-size: 0.82rem;
}

/* CTA BANNER */
.cta-banner {
    margin-top: 3rem;
    padding: 2.5rem 2.5rem;
    background: linear-gradient(135deg, var(--primary-deep) 0%, var(--primary-light) 100%);
    border-radius: var(--radius-2xl);
    text-align: center;
}

.cta-banner h3 {
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--white);
    margin-bottom: 0.5rem;
}

.cta-banner p {
    color: rgba(255, 255, 255, 0.5);
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
}

.btn {
    display: inline-block;
    padding: 13px 30px;
    background: var(--accent-gold);
    color: var(--white);
    border-radius: 50px;
    font-weight: 600;
    text-decoration: none;
    transition: all var(--transition-smooth);
    font-family: var(--font-sans);
}

.btn:hover {
    background: var(--accent-gold-light);
    transform: translateY(-2px);
    box-shadow: var(--shadow-gold);
}

/* FOOTER */
.site-footer {
    background: var(--primary-deep);
    color: rgba(255, 255, 255, 0.5);
    padding: 3rem 2rem 2rem;
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: 2rem;
    max-width: var(--max-width);
    margin: 0 auto;
}

.footer-grid h4 {
    color: var(--white);
    font-weight: 600;
    margin-bottom: 0.8rem;
    font-size: 0.92rem;
}

.footer-grid ul {
    list-style: none;
}

.footer-grid ul li {
    margin-bottom: 0.3rem;
    font-size: 0.84rem;
}

.footer-grid ul li a {
    color: inherit;
    text-decoration: none;
}

.footer-grid ul li a:hover {
    color: var(--accent-gold-light);
}

.footer-bottom {
    max-width: var(--max-width);
    margin: 2rem auto 0;
    padding-top: 1.5rem;
    border-top: 1px solid rgba(255, 255, 255, 0.06);
    text-align: center;
    font-size: 0.78rem;
    color: rgba(255, 255, 255, 0.3);
}

/* RESPONSIVE */
@media (max-width: 1024px) {
    .article-body {
        grid-template-columns: 1fr;
    }

    .article-sidebar {
        position: static;
    }

    .related-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .navbar {
        padding: 0 1.2rem;
    }

    .page-header {
        padding: 6rem 1.2rem 3rem;
    }

    .main-content {
        padding: 2rem 1rem 3rem;
    }

    .related-grid {
        grid-template-columns: 1fr;
    }

    .spec-table td:first-child {
        width: 110px;
        font-size: 0.78rem;
    }

    .spec-table td {
        padding: 0.6rem 0.7rem;
        font-size: 0.8rem;
    }

    .footer-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .cta-banner {
        padding: 2rem 1.2rem;
    }

    .cta-banner h3 {
        font-size: 1.25rem;
    }
}