/* ============================================
   GDM Research - Apple Style CSS
   ============================================ */

/* CSS Variables */
:root {
    /* Colors */
    --color-bg-primary: #1a1a2e;
    --color-bg-secondary: #16213e;
    --color-bg-tertiary: #0f3460;
    --color-accent: #e94560;
    --color-accent-light: #ff6b6b;
    --color-text-primary: #ffffff;
    --color-text-secondary: rgba(255, 255, 255, 0.7);
    --color-text-muted: rgba(255, 255, 255, 0.5);
    --color-glass: rgba(255, 255, 255, 0.05);
    --color-glass-border: rgba(255, 255, 255, 0.1);
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, #1a1a2e 0%, #16213e 50%, #0f3460 100%);
    --gradient-accent: linear-gradient(135deg, #e94560 0%, #ff6b6b 100%);
    --gradient-hero: linear-gradient(180deg, #1a1a2e 0%, #16213e 50%, #0f3460 100%);
    
    /* Typography */
    --font-primary: 'Inter', 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
    --font-size-5xl: 3.5rem;
    --font-size-6xl: 5rem;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 30px;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.3);
    --shadow-glow: 0 0 40px rgba(233, 69, 96, 0.3);
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Container */
    --container-max: 1200px;
    --container-padding: 2rem;
}

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

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

body {
    font-family: var(--font-primary);
    background: var(--color-bg-primary);
    color: var(--color-text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

ul {
    list-style: none;
}

/* Container */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* ============================================
   Navigation
   ============================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    padding: 1rem 0;
    transition: var(--transition-base);
    background: transparent;
}

.navbar.scrolled {
    background: rgba(26, 26, 46, 0.9);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-glass-border);
}

.nav-container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: var(--font-size-xl);
    font-weight: 700;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-menu {
    display: flex;
    gap: var(--spacing-lg);
}

.nav-link {
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
    transition: var(--transition-fast);
    position: relative;
}

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

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

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

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
}

.hamburger span {
    width: 24px;
    height: 2px;
    background: var(--color-text-primary);
    transition: var(--transition-base);
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
    padding: var(--spacing-3xl) 0;
}

.hero-background {
    position: absolute;
    inset: 0;
    z-index: -1;
}

.particles {
    position: absolute;
    inset: 0;
    background: var(--gradient-hero);
}

.particle {
    position: absolute;
    border-radius: 50%;
    background: rgba(233, 69, 96, 0.3);
    animation: float 15s infinite ease-in-out;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0) translateX(0);
        opacity: 0.3;
    }
    25% {
        transform: translateY(-30px) translateX(20px);
        opacity: 0.6;
    }
    50% {
        transform: translateY(-20px) translateX(-20px);
        opacity: 0.4;
    }
    75% {
        transform: translateY(-40px) translateX(10px);
        opacity: 0.5;
    }
}

.gradient-overlay {
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at center, transparent 0%, rgba(26, 26, 46, 0.5) 100%);
}

.hero-content {
    text-align: center;
    max-width: 900px;
    padding: 0 var(--container-padding);
    z-index: 1;
}

.hero-title {
    margin-bottom: var(--spacing-lg);
}

.title-line {
    display: block;
    font-size: var(--font-size-5xl);
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: -0.02em;
}

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

.hero-subtitle {
    font-size: var(--font-size-2xl);
    color: var(--color-text-secondary);
    margin-bottom: var(--spacing-sm);
    font-weight: 400;
}

.hero-description {
    font-size: var(--font-size-lg);
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-2xl);
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: var(--spacing-2xl);
    margin-bottom: var(--spacing-3xl);
}

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

.stat-number {
    display: block;
    font-size: var(--font-size-4xl);
    font-weight: 700;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.scroll-indicator {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    animation: bounce 2s infinite;
}

.scroll-arrow {
    width: 24px;
    height: 24px;
    border-right: 2px solid var(--color-text-muted);
    border-bottom: 2px solid var(--color-text-muted);
    transform: rotate(45deg);
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateY(0);
    }
    40% {
        transform: translateY(10px);
    }
    60% {
        transform: translateY(5px);
    }
}

/* ============================================
   Section Styles
   ============================================ */
.section {
    padding: var(--spacing-3xl) 0;
    position: relative;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section-tag {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-full);
    font-size: var(--font-size-xs);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-accent);
    margin-bottom: var(--spacing-md);
}

.section-title {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    letter-spacing: -0.02em;
}

.section-subtitle {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
    font-weight: 400;
}

.subsection-title {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

/* ============================================
   About Section
   ============================================ */
.about {
    background: linear-gradient(180deg, var(--color-bg-primary) 0%, var(--color-bg-secondary) 100%);
}

.about-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-3xl);
}

.about-card {
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    text-align: center;
    transition: var(--transition-base);
}

.about-card:hover {
    transform: translateY(-5px);
    border-color: var(--color-accent);
    box-shadow: var(--shadow-glow);
}

.card-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto var(--spacing-md);
    background: var(--gradient-accent);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
}

.card-icon svg {
    width: 32px;
    height: 32px;
    color: white;
}

.about-card h3 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-sm);
}

.about-card p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-base);
}

.highlight-text {
    color: var(--color-accent);
    font-weight: 600;
}

.epidemiology-section {
    margin-bottom: var(--spacing-3xl);
}

.epidemiology-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-lg);
}

.epi-card {
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    text-align: center;
    transition: var(--transition-base);
}

.epi-card:hover {
    transform: scale(1.05);
    border-color: var(--color-accent);
}

.epi-number {
    font-size: var(--font-size-5xl);
    font-weight: 700;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1;
}

.epi-unit {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    color: var(--color-accent);
}

.epi-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    margin-top: var(--spacing-sm);
}

/* ============================================
   Glass Effect & Image Container
   ============================================ */
.glass {
    background: var(--color-glass);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-lg);
}

.image-container {
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
    overflow: hidden;
}

.image-container img {
    width: 100%;
    border-radius: var(--radius-md);
    transition: var(--transition-base);
}

.image-container:hover img {
    transform: scale(1.02);
}

.knowledge-structure {
    margin-top: var(--spacing-2xl);
}

/* ============================================
   Breakthrough Section
   ============================================ */
.breakthrough {
    background: linear-gradient(180deg, var(--color-bg-secondary) 0%, var(--color-bg-tertiary) 100%);
}

.study-flow {
    margin-bottom: var(--spacing-3xl);
}

.metabolites-section {
    margin-top: var(--spacing-3xl);
}

.metabolites-intro {
    text-align: center;
    max-width: 700px;
    margin: 0 auto var(--spacing-2xl);
    color: var(--color-text-secondary);
}

.venn-diagram,
.metabolites-chart {
    margin-bottom: var(--spacing-2xl);
}

.biomarker-cards {
    margin: var(--spacing-3xl) 0;
}

.cards-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
}

.biomarker-card {
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: var(--transition-base);
}

.biomarker-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.card-header {
    margin-bottom: var(--spacing-md);
}

.badge {
    display: inline-block;
    padding: 4px 12px;
    border-radius: var(--radius-full);
    font-size: var(--font-size-xs);
    font-weight: 600;
}

.badge.primary {
    background: var(--gradient-accent);
}

.badge.secondary {
    background: rgba(15, 52, 96, 0.8);
}

.badge.accent {
    background: rgba(233, 69, 96, 0.3);
    border: 1px solid var(--color-accent);
}

.biomarker-card h4 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-sm);
}

.biomarker-card p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-md);
}

.card-footer {
    display: flex;
    justify-content: flex-end;
}

.correlation {
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-accent);
}

.interaction-chart,
.biomarkers-association {
    margin-top: var(--spacing-2xl);
}

/* ============================================
   Technology Section
   ============================================ */
.technology {
    background: linear-gradient(180deg, var(--color-bg-tertiary) 0%, var(--color-bg-primary) 100%);
}

.tech-features {
    max-width: 900px;
    margin: 0 auto var(--spacing-3xl);
}

.tech-feature {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: center;
    margin-bottom: var(--spacing-2xl);
}

.tech-feature.reverse {
    direction: rtl;
}

.tech-feature.reverse > * {
    direction: ltr;
}

.feature-visual {
    display: flex;
    justify-content: center;
}

.tech-icon {
    width: 120px;
    height: 120px;
    background: var(--gradient-accent);
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-glow);
}

.tech-icon svg {
    width: 48px;
    height: 48px;
    color: white;
}

.feature-content h3 {
    font-size: var(--font-size-2xl);
    margin-bottom: var(--spacing-sm);
}

.feature-content p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-lg);
}

.correlation-heatmap,
.pathway-enrichment {
    margin-top: var(--spacing-2xl);
}

/* ============================================
   Diagnosis Section
   ============================================ */
.diagnosis {
    background: linear-gradient(180deg, var(--color-bg-primary) 0%, var(--color-bg-secondary) 100%);
}

.performance-metrics {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-3xl);
}

.metric-card {
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    text-align: center;
    transition: var(--transition-base);
}

.metric-card:hover {
    transform: translateY(-5px);
    border-color: var(--color-accent);
}

.metric-card.primary {
    border-color: var(--color-accent);
    box-shadow: var(--shadow-glow);
}

.metric-value {
    font-size: var(--font-size-5xl);
    font-weight: 700;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1;
    margin-bottom: var(--spacing-sm);
}

.metric-label {
    font-size: var(--font-size-lg);
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.metric-desc {
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
}

.roc-curve,
.model-comparison {
    margin-top: var(--spacing-2xl);
}

/* ============================================
   Prediction Section
   ============================================ */
.prediction {
    background: linear-gradient(180deg, var(--color-bg-secondary) 0%, var(--color-bg-tertiary) 100%);
}

.prediction-intro {
    text-align: center;
    max-width: 700px;
    margin: 0 auto var(--spacing-3xl);
}

.highlight-paragraph {
    font-size: var(--font-size-xl);
    color: var(--color-text-secondary);
}

.highlight-number {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--color-accent);
}

.timeline-section {
    margin-bottom: var(--spacing-3xl);
    display: flex;
    flex-direction: column;
    align-items: center;
}

.timeline-section .subsection-title {
    width: 100%;
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.timeline {
    position: relative;
    max-width: 800px;
    width: 100%;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    width: 2px;
    height: 100%;
    background: linear-gradient(180deg, var(--color-accent) 0%, var(--color-bg-tertiary) 100%);
}

.timeline-item {
    display: flex;
    justify-content: center;
    align-items: flex-start;
    width: 100%;
    position: relative;
    margin-bottom: var(--spacing-xl);
}

.timeline-item:nth-child(odd) {
    flex-direction: row;
    padding-right: 50%;
}

.timeline-item:nth-child(even) {
    flex-direction: row-reverse;
    padding-left: 50%;
}

.timeline-marker {
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    background: var(--color-bg-primary);
    border: 2px solid var(--color-accent);
    border-radius: var(--radius-lg);
    padding: var(--spacing-sm) var(--spacing-md);
    text-align: center;
    min-width: 100px;
    z-index: 2;
}

.trimester {
    display: block;
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-accent);
}

.weeks {
    display: block;
    font-size: var(--font-size-xs);
    color: var(--color-text-muted);
}

.timeline-content {
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    max-width: 300px;
    width: 100%;
}

.timeline-item:nth-child(odd) .timeline-content {
    margin-right: var(--spacing-xl);
    text-align: right;
}

.timeline-item:nth-child(even) .timeline-content {
    margin-left: var(--spacing-xl);
    text-align: left;
}

.timeline-content h4 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-sm);
}

.timeline-content p {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

.first-trimester-chart,
.trimester-comparison,
.prediction-models {
    margin-top: var(--spacing-2xl);
}

/* ============================================
   Health Section
   ============================================ */
.health {
    background: linear-gradient(180deg, var(--color-bg-tertiary) 0%, var(--color-bg-primary) 100%);
}

.health-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-3xl);
}

.health-card {
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: var(--transition-base);
}

.health-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.card-header-section {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.health-icon {
    width: 56px;
    height: 56px;
    background: var(--gradient-accent);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
}

.health-icon svg {
    width: 28px;
    height: 28px;
    color: white;
}

.health-card h3 {
    font-size: var(--font-size-xl);
}

.risk-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.risk-list li {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid var(--color-glass-border);
}

.risk-list li:last-child {
    border-bottom: none;
}

.risk-dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    flex-shrink: 0;
}

.risk-dot.high {
    background: var(--color-accent);
}

.risk-dot.medium {
    background: #f59e0b;
}

.risk-dot.low {
    background: #10b981;
}

.risk-name {
    flex: 1;
    font-size: var(--font-size-base);
}

.risk-level {
    font-size: var(--font-size-xs);
    padding: 4px 10px;
    border-radius: var(--radius-full);
    font-weight: 600;
}

.risk-level:contains("高风险") {
    background: rgba(233, 69, 96, 0.2);
    color: var(--color-accent);
}

.health-tips {
    margin-top: var(--spacing-3xl);
}

.tips-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--spacing-lg);
}

.tip-card {
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    text-align: center;
    transition: var(--transition-base);
}

.tip-card:hover {
    transform: translateY(-5px);
    border-color: var(--color-accent);
}

.tip-number {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    color: var(--color-accent);
    opacity: 0.5;
    margin-bottom: var(--spacing-sm);
}

.tip-card h4 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-sm);
}

.tip-card p {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

/* ============================================
   Future Section
   ============================================ */
.future {
    background: linear-gradient(180deg, var(--color-bg-primary) 0%, var(--color-bg-secondary) 100%);
}

.future-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-3xl);
}

.future-card {
    background: var(--color-glass);
    border: 1px solid var(--color-glass-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: var(--transition-base);
}

.future-card:hover {
    transform: translateY(-5px);
    border-color: var(--color-accent);
    box-shadow: var(--shadow-glow);
}

.future-icon {
    width: 64px;
    height: 64px;
    background: var(--gradient-accent);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-md);
}

.future-icon svg {
    width: 32px;
    height: 32px;
    color: white;
}

.future-card h3 {
    font-size: var(--font-size-xl);
    margin-bottom: var(--spacing-md);
}

.future-card ul {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.future-card li {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
    padding-left: var(--spacing-md);
    position: relative;
}

.future-card li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--color-accent);
}

.research-timeline {
    margin-top: var(--spacing-3xl);
}

.timeline-horizontal {
    display: flex;
    justify-content: space-between;
    position: relative;
    padding-top: var(--spacing-xl);
}

.timeline-horizontal::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--color-accent) 0%, var(--color-bg-tertiary) 100%);
}

.timeline-h-item {
    text-align: center;
    position: relative;
    flex: 1;
}

.timeline-h-item::before {
    content: '';
    position: absolute;
    top: calc(-1 * var(--spacing-xl) + 1px);
    left: 50%;
    transform: translateX(-50%);
    width: 16px;
    height: 16px;
    background: var(--color-accent);
    border-radius: 50%;
    border: 3px solid var(--color-bg-primary);
}

.timeline-h-item.future-item::before {
    background: var(--color-bg-tertiary);
    border-color: var(--color-accent);
}

.timeline-h-year {
    font-size: var(--font-size-lg);
    font-weight: 700;
    color: var(--color-accent);
    margin-bottom: var(--spacing-sm);
}

.timeline-h-item.future-item .timeline-h-year {
    color: var(--color-text-muted);
}

.timeline-h-content h4 {
    font-size: var(--font-size-base);
    margin-bottom: var(--spacing-xs);
}

.timeline-h-content p {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

/* ============================================
   Footer
   ============================================ */
.footer {
    background: var(--color-bg-primary);
    border-top: 1px solid var(--color-glass-border);
    padding: var(--spacing-3xl) 0 var(--spacing-lg);
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: var(--spacing-2xl);
    margin-bottom: var(--spacing-2xl);
}

.footer-section h4 {
    font-size: var(--font-size-lg);
    margin-bottom: var(--spacing-md);
}

.footer-section p {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
}

.footer-section ul {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.footer-section a {
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    transition: var(--transition-fast);
}

.footer-section a:hover {
    color: var(--color-accent);
}

.footer-bottom {
    text-align: center;
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-glass-border);
}

.footer-bottom p {
    color: var(--color-text-muted);
    font-size: var(--font-size-sm);
    margin-bottom: var(--spacing-xs);
}

/* ============================================
   Animations
   ============================================ */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* Stagger animation delays */
.fade-in:nth-child(1) { transition-delay: 0.1s; }
.fade-in:nth-child(2) { transition-delay: 0.2s; }
.fade-in:nth-child(3) { transition-delay: 0.3s; }
.fade-in:nth-child(4) { transition-delay: 0.4s; }

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 1024px) {
    .about-grid,
    .cards-grid,
    .future-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .epidemiology-grid,
    .tips-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .health-grid {
        grid-template-columns: 1fr;
    }
    
    .tech-feature {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .tech-feature.reverse {
        direction: ltr;
    }
}

@media (max-width: 768px) {
    :root {
        --container-padding: 1rem;
        --font-size-5xl: 2.5rem;
        --font-size-4xl: 2rem;
        --font-size-3xl: 1.5rem;
    }
    
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: rgba(26, 26, 46, 0.98);
        flex-direction: column;
        padding: var(--spacing-lg);
        gap: var(--spacing-md);
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .hamburger {
        display: flex;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: var(--spacing-lg);
    }
    
    .about-grid,
    .cards-grid,
    .future-grid,
    .epidemiology-grid,
    .tips-grid,
    .performance-metrics {
        grid-template-columns: 1fr;
    }
    
    .timeline::before {
        left: 20px;
    }
    
    .timeline-item,
    .timeline-item:nth-child(even) {
        padding-left: 60px;
        padding-right: 0;
        justify-content: flex-start;
    }
    
    .timeline-marker {
        left: 20px;
        transform: translateX(-50%);
    }
    
    .timeline-item:nth-child(even) .timeline-content,
    .timeline-item:nth-child(odd) .timeline-content {
        margin-left: 0;
        margin-right: 0;
    }
    
    .timeline-horizontal {
        flex-direction: column;
        gap: var(--spacing-lg);
    }
    
    .timeline-horizontal::before {
        display: none;
    }
    
    .timeline-h-item::before {
        display: none;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .title-line {
        font-size: var(--font-size-3xl);
    }
    
    .hero-subtitle {
        font-size: var(--font-size-lg);
    }
    
    .section-title {
        font-size: var(--font-size-2xl);
    }
    
    .stat-number {
        font-size: var(--font-size-3xl);
    }
    
    .metric-value {
        font-size: var(--font-size-3xl);
    }
}

/* ============================================
   Print Styles
   ============================================ */
@media print {
    .navbar,
    .scroll-indicator,
    .particles {
        display: none;
    }
    
    .hero {
        min-height: auto;
        padding: var(--spacing-lg) 0;
    }
    
    .section {
        padding: var(--spacing-lg) 0;
        page-break-inside: avoid;
    }
    
    body {
        background: white;
        color: black;
    }
}