/* Google Fonts Import */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

/* CSS Variables for Theme System */
:root {
    /* Light Theme Palette (Sleek slate / steel blue) */
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --border-color: #e2e8f0;
    --border-hover: #cbd5e1;
    --text-color: #334155;
    --text-muted: #64748b;
    --heading-color: #0f172a;
    --accent-color: #3b82f6;
    --accent-muted: #eff6ff;
    --accent-hover: #2563eb;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
    --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
    /* Dark Theme Palette (Deep slate charcoal) */
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --border-color: #334155;
    --border-hover: #475569;
    --text-color: #94a3b8;
    --text-muted: #64748b;
    --heading-color: #f8fafc;
    --accent-color: #60a5fa;
    --accent-muted: #1e3a8a;
    --accent-hover: #93c5fd;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.5);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -2px rgba(0, 0, 0, 0.3);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    font-size: 16px;
    transition: var(--transition);
    -webkit-font-smoothing: antialiased;
}

a {
    color: var(--accent-color);
    text-decoration: none;
    transition: var(--transition);
}

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

/* Layout Container */
.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Global Header & Nav */
.site-header {
    border-bottom: 1px solid var(--border-color);
    background-color: var(--bg-color);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(8px);
    background-color: rgba(248, 250, 252, 0.8);
    transition: var(--transition);
}

[data-theme="dark"] .site-header {
    background-color: rgba(15, 23, 42, 0.8);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 4.5rem;
}

.logo-area a {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--heading-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    align-items: center;
    gap: 2rem;
}

.nav-link {
    font-size: 0.95rem;
    font-weight: 500;
    color: var(--text-color);
}

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

/* Theme Toggle Button */
.theme-toggle-btn {
    background: none;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 0.5rem;
    border-radius: 0.375rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    margin-left: 0.5rem;
}

.theme-toggle-btn:hover {
    border-color: var(--border-hover);
    background-color: var(--accent-muted);
    color: var(--accent-color);
}

.theme-toggle-btn svg {
    width: 1.15rem;
    height: 1.15rem;
    fill: currentColor;
}

/* Mobile Nav Styles */
.mobile-nav-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
}

/* Page Section Styles */
.section {
    padding: 4rem 0;
}

.section-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--heading-color);
    margin-bottom: 2rem;
    letter-spacing: -0.02em;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

/* Hero Section */
.hero-wrapper {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    padding: 3rem 0;
}

.hero-headline {
    font-size: 2.25rem;
    font-weight: 700;
    line-height: 1.25;
    color: var(--heading-color);
    letter-spacing: -0.03em;
    max-width: 800px;
}

.hero-bio {
    font-size: 1.125rem;
    color: var(--text-color);
    max-width: 750px;
    margin-bottom: 1.5rem;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.625rem 1.25rem;
    font-size: 0.95rem;
    font-weight: 500;
    border-radius: 0.375rem;
    transition: var(--transition);
    cursor: pointer;
}

.btn-primary {
    background-color: var(--accent-color);
    color: #ffffff;
}

.btn-primary:hover {
    background-color: var(--accent-hover);
    color: #ffffff;
}

.btn-secondary {
    border: 1px solid var(--border-color);
    background-color: var(--card-bg);
    color: var(--text-color);
}

.btn-secondary:hover {
    border-color: var(--border-hover);
    background-color: var(--accent-muted);
    color: var(--accent-color);
}

/* Capabilities Cards Grid */
.capabilities-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.capability-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    padding: 2rem;
    border-radius: 0.5rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.capability-card:hover {
    border-color: var(--accent-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.capability-icon {
    color: var(--accent-color);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
}

.capability-icon svg {
    width: 2rem;
    height: 2rem;
    stroke: currentColor;
    fill: none;
    stroke-width: 1.5;
}

.capability-title {
    font-size: 1.15rem;
    font-weight: 600;
    color: var(--heading-color);
    margin-bottom: 0.75rem;
}

.capability-desc {
    font-size: 0.95rem;
    color: var(--text-muted);
}

/* Career Timeline */
.timeline {
    position: relative;
    padding-left: 2rem;
    border-left: 2px solid var(--border-color);
    margin-left: 0.5rem;
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
}

.timeline-item:last-child {
    margin-bottom: 0;
}

.timeline-marker {
    position: absolute;
    width: 1rem;
    height: 1rem;
    background-color: var(--bg-color);
    border: 2px solid var(--accent-color);
    border-radius: 50%;
    left: calc(-2rem - 9px);
    top: 0.25rem;
    transition: var(--transition);
}

.timeline-item:hover .timeline-marker {
    background-color: var(--accent-color);
}

.timeline-meta {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: 0.5rem;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.timeline-title {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--heading-color);
}

.timeline-company {
    color: var(--accent-color);
    font-weight: 500;
    font-size: 1rem;
    margin-bottom: 0.25rem;
}

.timeline-date {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-muted);
}

.timeline-desc {
    font-size: 0.95rem;
    color: var(--text-color);
}

.timeline-desc li {
    margin-left: 1.25rem;
    margin-top: 0.25rem;
}

/* Publications Grid & Search Filter */
.pub-controls {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.search-wrapper {
    position: relative;
    flex: 1;
    min-width: 250px;
}

.search-input {
    width: 100%;
    padding: 0.625rem 1rem 0.625rem 2.5rem;
    font-size: 0.95rem;
    border: 1px solid var(--border-color);
    background-color: var(--card-bg);
    color: var(--text-color);
    border-radius: 0.375rem;
    transition: var(--transition);
}

.search-input:focus {
    border-color: var(--accent-color);
    outline: none;
}

.search-icon {
    position: absolute;
    left: 0.85rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
    pointer-events: none;
}

.search-icon svg {
    width: 1rem;
    height: 1rem;
    fill: none;
    stroke: currentColor;
    stroke-width: 2;
}

.filter-group {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.filter-btn {
    border: 1px solid var(--border-color);
    background-color: var(--card-bg);
    color: var(--text-color);
    padding: 0.5rem 1rem;
    border-radius: 0.375rem;
    font-size: 0.875rem;
    cursor: pointer;
    font-weight: 500;
    transition: var(--transition);
}

.filter-btn:hover, .filter-btn.active {
    border-color: var(--accent-color);
    background-color: var(--accent-muted);
    color: var(--accent-color);
}

.pub-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.pub-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    padding: 1.5rem;
    border-radius: 0.5rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.pub-card:hover {
    border-color: var(--border-hover);
    box-shadow: var(--shadow-md);
}

.pub-year-badge {
    display: inline-block;
    padding: 0.25rem 0.5rem;
    background-color: var(--accent-muted);
    color: var(--accent-color);
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: 0.25rem;
    margin-bottom: 0.75rem;
}

.pub-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--heading-color);
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.pub-authors {
    font-size: 0.925rem;
    color: var(--text-color);
    margin-bottom: 0.375rem;
}

.pub-venue {
    font-size: 0.9rem;
    font-style: italic;
    color: var(--text-muted);
    margin-bottom: 0.75rem;
}

.pub-links {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.pub-link {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 0.25rem 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: 0.25rem;
    color: var(--text-color);
}

.pub-link:hover {
    border-color: var(--accent-color);
    background-color: var(--accent-muted);
    color: var(--accent-color);
}

/* Service Lists */
.service-section-title {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--heading-color);
    margin-top: 2.5rem;
    margin-bottom: 1rem;
}

.service-section-title:first-of-type {
    margin-top: 0;
}

.service-list {
    list-style: none;
}

.service-list-item {
    position: relative;
    padding-left: 1.5rem;
    margin-bottom: 0.75rem;
    font-size: 0.95rem;
}

.service-list-item::before {
    content: "•";
    color: var(--accent-color);
    font-weight: bold;
    position: absolute;
    left: 0.25rem;
    top: 0;
}

/* Grid Layout for PC/Journals on Service Page */
.service-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 2rem;
    margin-top: 1.5rem;
}

/* Education Layout */
.education-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.education-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    padding: 1.5rem;
    border-radius: 0.5rem;
}

.education-degree {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--heading-color);
}

.education-school {
    color: var(--accent-color);
    font-weight: 500;
    font-size: 0.95rem;
}

.education-year {
    font-size: 0.875rem;
    color: var(--text-muted);
}

/* Footer styling */
.site-footer {
    border-top: 1px solid var(--border-color);
    padding: 3rem 0;
    margin-top: 4rem;
    text-align: center;
    font-size: 0.875rem;
    color: var(--text-muted);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

/* Contact Details */
.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1.5rem;
}

.contact-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    padding: 1.5rem;
    border-radius: 0.5rem;
    display: flex;
    gap: 1rem;
    align-items: flex-start;
}

.contact-icon {
    color: var(--accent-color);
}

.contact-icon svg {
    width: 1.5rem;
    height: 1.5rem;
    stroke: currentColor;
    fill: none;
    stroke-width: 2;
}

.contact-label {
    font-weight: 600;
    color: var(--heading-color);
    margin-bottom: 0.25rem;
    font-size: 0.95rem;
}

.contact-value {
    font-size: 0.9rem;
    color: var(--text-color);
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .container {
        padding: 0 1.25rem;
    }
    
    .nav-menu {
        display: none; /* Mobile nav can be collapsed */
    }
    
    .mobile-nav-toggle {
        display: block;
    }
    
    .hero-headline {
        font-size: 1.75rem;
    }
    
    .pub-controls {
        flex-direction: column;
        align-items: stretch;
    }
    
    .search-wrapper {
        width: 100%;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
    
    .service-grid {
        grid-template-columns: 1fr;
    }
}

/* Visiting positions grid */
.visiting-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.visiting-card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    padding: 1.5rem;
    border-radius: 0.5rem;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.visiting-card:hover {
    border-color: var(--border-hover);
    box-shadow: var(--shadow-md);
}

/* Awards List */
.awards-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
    margin-top: 1.5rem;
}

.award-item {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    gap: 1.5rem;
    padding-bottom: 1rem;
    border-bottom: 1px dashed var(--border-color);
}

.award-item:last-child {
    border-bottom: none;
}

.award-text {
    font-size: 0.975rem;
    color: var(--text-color);
    line-height: 1.5;
}

.award-year {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-weight: 500;
    white-space: nowrap;
    border: 1px solid var(--border-color);
    padding: 0.15rem 0.4rem;
    border-radius: 0.25rem;
}