/* Professional Academic Website Design */

/* CSS Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Professional Color Palette - Academic & Refined */
    --primary-navy: #1e3a5f;
    --primary-blue: #2c5282;
    --accent-teal: #2d7a7f;
    --accent-gold: #d4a574;
    --accent-burgundy: #8b4d6d;
    
    /* Neutrals - Professional */
    --bg-light: #f5f6f8;
    --bg-white: #fafbfc;
    --bg-card: #ffffff;
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    --border-color: #d1d5db;
    --shadow: rgba(0, 0, 0, 0.06);
    
    /* Typography - Academic */
    --font-primary: 'Merriweather', 'Georgia', serif;
    --font-heading: 'Open Sans', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    
    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 1.5rem;
    --space-lg: 2rem;
    --space-xl: 3rem;
    --space-2xl: 4rem;
    
    /* Layout */
    --container-max: 1200px;
    --header-height: 90px;
    
    /* Border radius */
    --radius: 6px;
    --radius-sm: 4px;
    --radius-lg: 8px;
}

body {
    font-family: var(--font-primary);
    font-size: 17px;
    line-height: 1.8;
    color: var(--text-primary);
    background-color: var(--bg-light);
}

/* Academic Header - Clean & Professional */
.header {
    background: var(--bg-white);
    border-bottom: 1px solid var(--border-color);
    padding: var(--space-lg) 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.04);
    transition: all 0.3s ease;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo a {
    font-family: var(--font-heading);
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--primary-navy);
    text-decoration: none;
    letter-spacing: 0.5px;
    transition: all 0.3s ease;
}

.logo a:hover {
    color: var(--primary-blue);
}

.tagline {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    margin-top: 0.25rem;
    font-weight: 400;
    font-style: italic;
    transition: all 0.3s ease;
}

.menu-toggle {
    display: none;
    background: transparent;
    border: 2px solid var(--primary-navy);
    color: var(--primary-navy);
    font-size: 1.25rem;
    cursor: pointer;
    padding: 0.5rem 0.75rem;
    border-radius: var(--radius-sm);
    transition: all 0.3s ease;
}

.menu-toggle:hover {
    background: var(--primary-navy);
    color: white;
}

.main-nav {
    display: flex;
    gap: var(--space-lg);
    align-items: center;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    padding: var(--space-xs) 0;
    font-weight: 500;
    font-size: 0.9375rem;
    transition: all 0.3s ease;
    position: relative;
    font-family: var(--font-heading);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-navy);
    transition: width 0.3s ease;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-navy);
}

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

/* Professional Hero Section */
.hero-section {
    background: linear-gradient(135deg, #1e3a5f 0%, #2c5282 100%);
    color: white;
    padding: var(--space-2xl) 0;
    min-height: 550px;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    opacity: 0.1;
    background-image: repeating-linear-gradient(
        45deg,
        transparent,
        transparent 10px,
        rgba(255,255,255,0.03) 10px,
        rgba(255,255,255,0.03) 20px
    );
    pointer-events: none;
}

.hero-content {
    text-align: left;
    max-width: 900px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-family: var(--font-heading);
    font-size: clamp(2.25rem, 5vw, 3.5rem);
    font-weight: 700;
    margin-bottom: var(--space-lg);
    line-height: 1.2;
    color: white;
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: var(--space-xl);
    font-weight: 400;
    line-height: 1.7;
    color: rgba(255, 255, 255, 0.95);
    max-width: 700px;
}

.hero-actions {
    display: flex;
    gap: var(--space-md);
    flex-wrap: wrap;
}

/* Professional Button Styles */
.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    text-decoration: none;
    border-radius: var(--radius);
    font-weight: 600;
    font-size: 0.9375rem;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
    font-family: var(--font-heading);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-size: 0.875rem;
}

.btn-primary {
    background: var(--accent-gold);
    color: var(--text-primary);
    box-shadow: 0 4px 12px rgba(212, 165, 116, 0.3);
}

.btn-primary:hover {
    background: #c99566;
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(212, 165, 116, 0.4);
}

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid white;
}

.btn-secondary:hover {
    background: white;
    color: var(--primary-navy);
}

/* Clean Card Designs */
.intro-section {
    padding: var(--space-2xl) 0;
    background: var(--bg-white);
}

.intro-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-lg);
}

.intro-card, .highlight-card, .career-card, .publication-item, .research-area-card, .cv-section {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    padding: var(--space-lg);
    transition: all 0.25s ease;
    box-shadow: 0 1px 3px var(--shadow);
}

.intro-card:hover,
.highlight-card:hover,
.career-card:hover,
.publication-item:hover,
.research-area-card:hover {
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    transform: translateY(-2px);
    border-color: #c4c9d1;
}

.intro-card {
    border-top: 3px solid var(--accent-teal);
}

.intro-card .icon {
    font-size: 2.5rem;
    margin-bottom: var(--space-md);
}

.intro-card h2 {
    color: var(--primary-navy);
    margin-bottom: var(--space-sm);
    font-size: 1.5rem;
    font-weight: 700;
    font-family: var(--font-heading);
}

.intro-card p {
    color: var(--text-secondary);
    line-height: 1.8;
}

/* Section Titles */
.section-title {
    font-family: var(--font-heading);
    font-size: clamp(1.875rem, 4vw, 2.5rem);
    font-weight: 600;
    color: var(--primary-navy);
    margin-bottom: var(--space-lg);
    margin-top: var(--space-xl);
    text-align: center;
    padding-bottom: var(--space-sm);
    border-bottom: 1px solid var(--border-color);
}

.section-title::after {
    content: '';
    display: block;
    width: 60px;
    height: 2px;
    background: var(--accent-gold);
    margin: var(--space-sm) auto 0;
}

/* Highlights Section */
.highlights-section {
    padding: var(--space-2xl) 0;
    background: var(--bg-light);
}

.intro-section {
    background: var(--bg-light);
}

.publication-stats {
    background: var(--bg-light);
}

.highlights-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--space-lg);
}

.highlight-card {
    border-left: 2px solid var(--accent-burgundy);
    padding: var(--space-xl);
}

.highlight-card .year {
    display: inline-block;
    background: var(--primary-navy);
    color: white;
    padding: 0.25rem 0.875rem;
    border-radius: var(--radius-sm);
    font-size: 0.8125rem;
    font-weight: 600;
    margin-bottom: var(--space-md);
    font-family: var(--font-heading);
    letter-spacing: 0.3px;
}

.highlight-card h3 {
    color: var(--text-primary);
    margin-bottom: var(--space-sm);
    font-size: 1.375rem;
    font-weight: 700;
    font-family: var(--font-heading);
}

.highlight-card p {
    color: var(--text-secondary);
    margin-bottom: var(--space-md);
    line-height: 1.8;
}

.read-more {
    color: var(--primary-blue);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9375rem;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
}

.read-more:hover {
    color: var(--accent-teal);
    transform: translateX(4px);
}

.read-more::after {
    content: '→';
    transition: transform 0.3s ease;
}

.read-more:hover::after {
    transform: translateX(4px);
}

/* Page Header */
.page-header {
    background: var(--primary-navy);
    color: white;
    padding: var(--space-xl) 0;
    text-align: center;
    position: relative;
}

.page-header h1 {
    font-family: var(--font-heading);
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 700;
    margin-bottom: var(--space-sm);
    color: white;
}

.page-subtitle {
    font-size: 1.125rem;
    color: rgba(255, 255, 255, 0.9);
    font-style: italic;
}

/* Add spacing before first content section after page-header */
.page-header + .container {
    padding-top: var(--space-2xl);
}

/* Publication Styles */
.publication-stats {
    padding: var(--space-lg) 0;
    background: var(--bg-white);
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    gap: var(--space-lg);
}

.stat-card {
    background: var(--primary-navy);
    color: white;
    padding: var(--space-lg);
    border-radius: var(--radius);
    text-align: center;
    box-shadow: 0 2px 8px rgba(30, 58, 95, 0.2);
    transition: all 0.25s ease;
}

.stat-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(30, 58, 95, 0.3);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--space-xs);
    color: white;
}

.stat-label {
    font-size: 0.9375rem;
    color: rgba(255, 255, 255, 0.95);
    font-weight: 500;
}

.publication-filters {
    padding: var(--space-lg) 0;
    background: var(--bg-white);
    border-bottom: 2px solid var(--border-color);
}

.filter-buttons {
    display: flex;
    gap: var(--space-sm);
    flex-wrap: wrap;
    justify-content: center;
}

.filter-btn {
    padding: 0.625rem 1.25rem;
    background: var(--bg-white);
    border: 2px solid var(--border-color);
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.9375rem;
    color: var(--text-secondary);
    font-weight: 500;
    font-family: var(--font-heading);
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--primary-navy);
    color: white;
    border-color: var(--primary-navy);
}

.publications-list {
    padding: 0 0 var(--space-xl) 0;
}

.publication-section {
    margin-top: var(--space-xl);
}

.publication-item {
    display: flex;
    gap: var(--space-lg);
    margin-bottom: var(--space-lg);
    padding: var(--space-lg);
    border-left: 2px solid var(--primary-blue);
}

.publication-item.featured {
    background: rgba(44, 82, 130, 0.03);
    border-left-color: var(--accent-gold);
}

.pub-year {
    min-width: 90px;
    font-weight: 700;
    font-size: 1.5rem;
    color: var(--primary-navy);
    font-family: var(--font-heading);
}

.pub-content h3 {
    color: var(--text-primary);
    margin-bottom: var(--space-xs);
    font-size: 1.25rem;
    font-weight: 600;
    line-height: 1.5;
}

.pub-authors,
.pub-journal,
.pub-doi {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    margin-bottom: var(--space-xs);
    line-height: 1.8;
}

.pub-highlight {
    color: var(--accent-burgundy);
    font-size: 0.875rem;
    font-weight: 600;
    margin-top: var(--space-xs);
    font-style: italic;
}

.pub-note {
    font-style: italic;
    color: var(--text-muted);
    font-size: 0.9375rem;
}

.btn-link {
    color: var(--primary-blue);
    text-decoration: none;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
}

.btn-link:hover {
    color: var(--accent-teal);
}

/* Research Areas */
.research-areas {
    padding: var(--space-2xl) 0;
}


.research-area-card {
    display: flex;
    gap: var(--space-lg);
    align-items: flex-start;
    margin-bottom: var(--space-lg);
    padding: var(--space-xl);
    border-top: 2px solid var(--accent-teal);
}

.area-icon {
    font-size: 3rem;
    flex-shrink: 0;
    opacity: 0.8;
}

.area-content {
    flex: 1;
}

.research-area-card h3 {
    color: var(--primary-navy);
    margin-bottom: var(--space-md);
    font-size: 1.625rem;
    font-weight: 700;
    font-family: var(--font-heading);
}

.research-area-card ul {
    list-style: none;
    padding-left: 0;
}

.research-area-card li {
    padding: var(--space-xs) 0;
    padding-left: var(--space-lg);
    position: relative;
    color: var(--text-secondary);
    line-height: 1.8;
}

.research-area-card li::before {
    content: "■";
    position: absolute;
    left: 0;
    color: var(--accent-teal);
    font-size: 0.875rem;
}

/* Timeline Styles */
.timeline {
    padding: var(--space-xl) 0;
}

.timeline-item {
    display: flex;
    gap: var(--space-lg);
    margin-bottom: var(--space-xl);
    padding-left: var(--space-lg);
    border-left: 2px solid var(--border-color);
}

.timeline-year {
    min-width: 100px;
    font-weight: 700;
    font-size: 1.375rem;
    color: var(--primary-navy);
    font-family: var(--font-heading);
}

.timeline-content h3 {
    color: var(--primary-navy);
    margin-bottom: var(--space-xs);
    font-size: 1.375rem;
    font-weight: 700;
    font-family: var(--font-heading);
}

.timeline-content p {
    color: var(--text-secondary);
    line-height: 1.8;
}

.career-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--space-lg);
}

.career-card {
    border-top: 2px solid var(--primary-blue);
}

.career-card h3 {
    color: var(--accent-burgundy);
    margin-bottom: var(--space-xs);
    font-size: 0.9375rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-family: var(--font-heading);
}

.career-card h4 {
    color: var(--primary-navy);
    margin-bottom: var(--space-xs);
    font-size: 1.25rem;
    font-weight: 700;
    font-family: var(--font-heading);
}

.career-card p {
    color: var(--text-secondary);
    line-height: 1.8;
}

/* Current Work Section */
.current-work {
    padding: var(--space-2xl) 0;
    background: rgba(44, 82, 130, 0.03);
}

.current-work-content {
    max-width: 900px;
    margin: 0 auto;
}

.technology-list {
    list-style: none;
    padding: 0;
}

.technology-list li {
    padding: var(--space-sm) 0;
    padding-left: var(--space-lg);
    position: relative;
    color: var(--text-secondary);
    line-height: 1.8;
}

.technology-list li::before {
    content: "▶";
    position: absolute;
    left: 0;
    color: var(--accent-gold);
    font-size: 0.875rem;
}

.cv-container {
    padding: var(--space-xl) 0;
}

.cv-download {
    text-align: center;
    margin: var(--space-xl) 0;
}

.cv-section {
    margin-bottom: var(--space-lg);
}

.cv-section h2 {
    color: var(--primary-navy);
    border-bottom: 1px solid var(--border-color);
    padding-bottom: var(--space-sm);
    margin-bottom: var(--space-lg);
    font-family: var(--font-heading);
    position: relative;
    padding-bottom: var(--space-md);
}

.cv-section h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 80px;
    height: 3px;
    background: var(--accent-gold);
}

.cv-timeline {
    padding: var(--space-lg) 0;
}

.cv-entry {
    display: flex;
    gap: var(--space-lg);
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-lg);
    border-bottom: 1px solid var(--border-color);
}

.cv-entry:last-child {
    border-bottom: none;
}

.cv-year {
    min-width: 120px;
    font-weight: 700;
    color: var(--primary-navy);
    font-family: var(--font-heading);
}

.grants-list,
.awards-list {
    list-style: none;
    padding: 0;
}

.grants-list li,
.awards-list li {
    padding: var(--space-sm) 0;
    padding-left: var(--space-lg);
    position: relative;
    color: var(--text-secondary);
    line-height: 1.8;
}

.grants-list li::before,
.awards-list li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--primary-blue);
    font-weight: bold;
    font-size: 1.2rem;
}

/* Utility Classes */
.lead {
    font-size: 1.25rem;
    line-height: 1.9;
    color: var(--text-primary);
    margin-bottom: var(--space-lg);
}

/* Footer */
.footer {
    background: var(--primary-navy);
    color: white;
    padding: var(--space-xl) 0;
    margin-top: var(--space-2xl);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-xl);
    margin-bottom: var(--space-xl);
}

.footer-section h3 {
    margin-bottom: var(--space-md);
    color: var(--accent-gold);
    font-family: var(--font-heading);
    font-weight: 700;
}

.footer-section p,
.footer-section a {
    color: rgba(255, 255, 255, 0.9);
    text-decoration: none;
    line-height: 1.8;
}

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

.footer-bottom {
    text-align: center;
    padding-top: var(--space-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    color: rgba(255, 255, 255, 0.8);
    font-size: 0.9375rem;
}

/* Main Content */
.main-content {
    min-height: calc(100vh - 400px);
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .menu-toggle {
        display: block;
    }
    
    .main-nav {
        display: none;
        flex-direction: column;
        align-items: stretch;
        gap: var(--space-xs);
        background: white;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        padding: var(--space-lg);
        box-shadow: 0 4px 12px var(--shadow);
    }
    
    .main-nav.active {
        display: flex;
    }
    
    .nav-link {
        display: block;
        text-align: center;
        padding: var(--space-sm);
    }
    
    .research-area-card,
    .timeline-item,
    .cv-entry,
    .publication-item {
        flex-direction: column;
    }
    
    .container {
        padding: 0 var(--space-md);
    }
    
    .hero-section {
        min-height: 500px;
        padding: var(--space-xl) 0;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .intro-grid,
    .highlights-grid,
    .career-grid {
        grid-template-columns: 1fr;
    }
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Print Styles */
@media print {
    .header,
    .footer,
    .main-nav {
        display: none;
    }
    
    .hero-section {
        min-height: auto;
        padding: var(--space-lg) 0;
    }
}