/* ========================================
   CSS Variables & Reset
   ======================================== */
:root {
    /* Colors - Academic with dark gray accent */
    --color-primary: #2c3e50;
    --color-secondary: #34495e;
    --color-accent: #4a5568;
    --color-accent-light: #718096;
    --color-text: #2c3e50;
    --color-text-light: #7f8c8d;
    --color-background: #fdfbf7;
    --color-surface: #ffffff;
    --color-border: #ecf0f1;
    
    /* Typography */
    --font-serif: 'Crimson Pro', Georgia, serif;
    --font-mono: 'JetBrains Mono', monospace;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;
    
    /* Transitions */
    --transition-smooth: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-bounce: all 0.4s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

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

html {
    scroll-behavior: smooth;
    font-size: 18px;
}

body {
    font-family: var(--font-serif);
    color: var(--color-text);
    background-color: var(--color-background);
    line-height: 1.7;
    overflow-x: hidden;
}

/* ========================================
   Navigation
   ======================================== */
.nav-container {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(253, 251, 247, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--color-border);
    animation: slideDown 0.6s ease-out;
}

@keyframes slideDown {
    from {
        transform: translateY(-100%);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}

.nav-content {
    max-width: 1300px;
    margin: 0 auto;
    padding: 1.5rem 0rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-primary);
    text-decoration: none;
    letter-spacing: -0.02em;
    transition: var(--transition-smooth);
}

.logo:hover {
    color: var(--color-accent);
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-link {
    color: var(--color-text-light);
    text-decoration: none;
    font-size: 1.25rem;
    position: relative;
    transition: var(--transition-smooth);
    font-weight: 500;
}

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

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

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

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

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

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

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: var(--spacing-lg);
    align-items: center;
}

.hero-text {
    animation: fadeInUp 0.8s ease-out 0.2s both;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-title {
    font-size: 4rem;
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: var(--spacing-md);
    color: var(--color-primary);
}

.hero-title .line {
    display: block;
    opacity: 0;
    animation: fadeInUp 0.8s ease-out both;
}

.hero-title .line:nth-child(1) {
    animation-delay: 0.3s;
}

.hero-title .line:nth-child(2) {
    animation-delay: 0.5s;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
    max-width: 600px;
    line-height: 1.6;
    animation: fadeInUp 0.8s ease-out 0.7s both;
}

/* Hero Actions/Buttons */
.hero-actions {
    display: flex;
    gap: var(--spacing-sm);
    animation: fadeInUp 0.8s ease-out 0.9s both;
    flex-wrap: wrap;
}

.btn-primary, .btn-secondary {
    display: inline-flex;
    align-items: center;
    padding: 0.875rem 1.75rem;
    border-radius: 8px;
    font-weight: 600;
    text-decoration: none;
    transition: var(--transition-smooth);
    font-size: 1rem;
}

.btn-primary {
    background: var(--color-accent);
    color: white;
    border: 2px solid var(--color-accent);
}

.btn-primary:hover {
    background: var(--color-accent-light);
    border-color: var(--color-accent-light);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(74, 85, 104, 0.3);
}

.btn-secondary {
    background: transparent;
    color: var(--color-accent);
    border: 2px solid var(--color-accent);
}

.btn-secondary:hover {
    background: var(--color-accent);
    color: white;
    transform: translateY(-2px);
}

.hero-details {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    animation: fadeInUp 0.8s ease-out 0.9s both;
}

.detail-item {
    display: flex;
    align-items: baseline;
    gap: var(--spacing-sm);
}

.detail-label {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-accent);
    font-weight: 500;
    min-width: 120px;
}

.detail-value {
    color: var(--color-text);
    font-size: 1rem;
}

/* Hero Decorative Elements */
.hero-decorative {
    position: relative;
    height: 400px;
}

.decorative-circle {
    position: absolute;
    border-radius: 50%;
    opacity: 0.08;
}

.circle-1 {
    width: 500px;
    height: 500px;
    background: var(--color-accent);
    top: 0;
    right: 50;
    animation: float 6s ease-in-out infinite;
}

.circle-2 {
    width: 300px;
    height: 300px;
    background: var(--color-primary);
    bottom: 50px;
    right: 100px;
    animation: float 8s ease-in-out infinite 1s;
}

.circle-3 {
    width: 200px;
    height: 200px;
    background: var(--color-accent-light);
    top: 150px;
    right: 50px;
    animation: float 7s ease-in-out infinite 2s;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0px);
    }
    50% {
        transform: translateY(-20px);
    }
}

/* ========================================
   Content Sections
   ======================================== */
.content-section {
    padding: var(--spacing-lg) var(--spacing-md);
}

/* Reduce spacing for highlights section on home page */
.content-section.highlights {
    padding-top: var(--spacing-xs);
}

.alt-section {
    background: linear-gradient(to bottom, var(--color-background) 0%, #f8f6f3 100%);
}

.section-container {
    max-width: 1200px;
    margin: 0 auto;
}

.section-header {
    margin-bottom: var(--spacing-lg);
    text-align: left;
}

.section-title {
    font-size: 3rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 0;
    width: 60px;
    height: 4px;
    background: var(--color-accent);
}

.section-description {
    font-size: 1.25rem;
    color: var(--color-text-light);
    max-width: 700px;
    line-height: 1.6;
}

/* ========================================
   Cards
   ======================================== */
.card {
    background: var(--color-surface);
    border-radius: 12px;
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    border: 1px solid var(--color-border);
    transition: var(--transition-smooth);
    position: relative;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.08);
    border-color: var(--color-accent);
}

.featured-card {
    background: linear-gradient(135deg, #fff 0%, #f8f9fa 100%);
    border: 2px solid var(--color-accent);
    padding: var(--spacing-lg);
}

.card-badge {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-accent);
    background: rgba(74, 85, 104, 0.1);
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    margin-bottom: var(--spacing-sm);
    font-weight: 500;
}

.card-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-xs);
    line-height: 1.3;
}

.card-date {
    font-size: 0.9rem;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-sm);
    font-family: var(--font-mono);
}

.card-excerpt {
    color: var(--color-text);
    margin-bottom: var(--spacing-sm);
    line-height: 1.7;
}

.card-link {
    display: inline-flex;
    align-items: center;
    color: var(--color-accent);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition-smooth);
    gap: 0.5rem;
}

.card-link::after {
    content: '→';
    transition: var(--transition-smooth);
}

.card-link:hover {
    color: var(--color-accent-light);
}

.card-link:hover::after {
    transform: translateX(4px);
}

/* Cards Grid */
.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: var(--spacing-md);
}

/* Flexible Cards Grid - for cards with different sizes */
.cards-grid-flexible {
    display: grid;
    grid-template-columns: repeat(12, 1fr);
    gap: var(--spacing-md);
}

/* Card with Image */
.card-with-image {
    background: var(--color-surface);
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid var(--color-border);
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
    position: relative;
}

.card-with-image:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 24px rgba(0, 0, 0, 0.12);
    border-color: var(--color-accent);
}

/* Size variants for flexible grid */
.card-with-image.large {
    grid-column: span 7;
}

.card-with-image.medium {
    grid-column: span 5;
}

.card-with-image.small {
    grid-column: span 4;
}

.card.small {
    grid-column: span 4;
}

/* Default card in flexible grid */
.cards-grid-flexible > .card {
    grid-column: span 4;
}

/* Card Image */
.card-image {
    width: 100%;
    height: 250px;
    background-size: cover;
    background-position: center;
    position: relative;
}

.card-with-image.large .card-image {
    height: 300px;
}

.card-with-image.medium .card-image {
    height: 220px;
}

/* Card Content (for image cards) */
.card-content {
    padding: var(--spacing-md);
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.card-content .card-title {
    font-size: 1.5rem;
}

.card-content .card-excerpt {
    flex-grow: 1;
}

.interactive-card {
    transition: var(--transition-bounce);
}

.interactive-card:hover {
    transform: translateY(-8px) scale(1.02);
}

/* ========================================
   Subsections
   ======================================== */
.subsection {
    margin-top: var(--spacing-lg);
}

.subsection-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-secondary);
    margin-bottom: var(--spacing-md);
    border-left: 4px solid var(--color-accent);
    padding-left: var(--spacing-sm);
}

/* ========================================
   Research Section
   ======================================== */
.research-highlight {
    background: var(--color-surface);
    border-radius: 12px;
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    border: 2px solid var(--color-border);
}

.highlight-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
}

.highlight-text {
    font-size: 1.125rem;
    line-height: 1.8;
    color: var(--color-text);
    margin-bottom: var(--spacing-md);
}

.research-areas {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.research-tag {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    padding: 0.5rem 1rem;
    background: rgba(74, 85, 104, 0.1);
    color: var(--color-accent);
    border-radius: 20px;
    font-weight: 500;
}

/* Timeline */
.timeline {
    position: relative;
    padding-left: 2rem;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--color-border);
}

.timeline-item {
    position: relative;
    margin-bottom: var(--spacing-lg);
    padding-left: var(--spacing-md);
}

.timeline-marker {
    position: absolute;
    left: -6px;
    top: 6px;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--color-accent);
    border: 3px solid var(--color-background);
}

.timeline-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: 0.25rem;
}

.timeline-org {
    color: var(--color-text-light);
    margin-bottom: 0.25rem;
}

.timeline-date {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--color-text-light);
}

/* ========================================
   Projects Section
   ======================================== */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-md);
}

.project-card {
    background: var(--color-surface);
    border-radius: 12px;
    overflow: hidden;
    border: 1px solid var(--color-border);
    transition: var(--transition-smooth);
    display: flex;
    flex-direction: column;
}

.project-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.12);
}

.large-card {
    grid-column: span 2;
}

.project-image {
    width: 100%;
    height: 200px;
    background-size: cover;
    background-position: center;
    position: relative;
}

.large-card .project-image {
    height: 300px;
}

.project-content {
    padding: var(--spacing-md);
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.project-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
}

.project-description {
    color: var(--color-text);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
    flex-grow: 1;
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.tag {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    padding: 0.25rem 0.75rem;
    background: var(--color-border);
    color: var(--color-text-light);
    border-radius: 4px;
}

/* ========================================
   Post List
   ======================================== */
.post-list {
    list-style: none;
    margin-top: var(--spacing-lg);
}

.post-list-item {
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid var(--color-border);
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    gap: var(--spacing-sm);
}

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

.post-list-title {
    color: var(--color-text);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition-smooth);
    flex-grow: 1;
}

.post-list-title:hover {
    color: var(--color-accent);
}

.post-list-date {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--color-text-light);
    white-space: nowrap;
}

/* ========================================
   CV Page Specific
   ======================================== */
.cv-section {
    margin-bottom: var(--spacing-lg);
}

.cv-section-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--color-accent);
    padding-bottom: var(--spacing-xs);
}

.cv-item {
    margin-bottom: var(--spacing-md);
}

.cv-item-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-secondary);
    margin-bottom: 0.25rem;
}

.cv-item-meta {
    color: var(--color-text-light);
    font-style: italic;
    margin-bottom: var(--spacing-xs);
}

.cv-item-description {
    color: var(--color-text);
    line-height: 1.6;
}

/* ========================================
   Footer
   ======================================== */
.footer {
    background: var(--color-primary);
    color: white;
    padding: var(--spacing-lg) var(--spacing-md);
    margin-top: var(--spacing-xl);
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-text {
    color: rgba(255, 255, 255, 0.8);
}

.footer-links {
    display: flex;
    gap: var(--spacing-md);
}

.footer-link {
    color: white;
    text-decoration: none;
    transition: var(--transition-smooth);
}

.footer-link:hover {
    color: var(--color-accent-light);
}

/* ========================================
   Responsive Design
   ======================================== */
@media (max-width: 1024px) {
    .hero-content {
        grid-template-columns: 1fr;
    }
    
    .hero-decorative {
        display: none;
    }
    
    .hero-title {
        font-size: 3rem;
    }
    
    .large-card {
        grid-column: span 1;
    }
    
    /* Flexible grid adjustments for tablet */
    .card-with-image.large,
    .card-with-image.medium,
    .card-with-image.small,
    .cards-grid-flexible > .card {
        grid-column: span 6;
    }
}

@media (max-width: 768px) {
    html {
        font-size: 14px;
    }
    
    .nav-content {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-links {
        gap: 1rem;
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .hero {
        padding: var(--spacing-lg) var(--spacing-sm);
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.25rem;
    }
    
    .hero-actions {
        flex-direction: column;
    }
    
    .btn-primary, .btn-secondary {
        width: 100%;
        justify-content: center;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .cards-grid {
        grid-template-columns: 1fr;
    }
    
    /* All cards full width on mobile */
    .cards-grid-flexible {
        grid-template-columns: 1fr;
    }
    
    .card-with-image.large,
    .card-with-image.medium,
    .card-with-image.small,
    .cards-grid-flexible > .card {
        grid-column: span 1;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        flex-direction: column;
        gap: var(--spacing-sm);
        text-align: center;
    }
    
    .post-list-item {
        flex-direction: column;
        align-items: flex-start;
    }
}

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

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

/* Custom Scrollbar */
::-webkit-scrollbar {
    width: 12px;
}

::-webkit-scrollbar-track {
    background: var(--color-background);
}

::-webkit-scrollbar-thumb {
    background: var(--color-accent);
    border-radius: 6px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--color-accent-light);
}