/* ================================
   Reset & Base Styles
   ================================ */

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

:root {
    /* Color Palette - Dark Theme */
    --bg-primary: #0a0a0a;
    --bg-secondary: #141414;
    --bg-tertiary: #1a1a1a;
    --text-primary: #e8e8e8;
    --text-secondary: #a0a0a0;
    --text-muted: #6a6a6a;
    --accent: #3b82f6;
    --accent-hover: #2563eb;
    --border: #2a2a2a;
    
    /* Typography */
    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Courier New', monospace;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;
    
    /* Transitions */
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ================================
   Navigation
   ================================ */

.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: rgba(10, 10, 10, 0.8);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
    padding: var(--spacing-sm) 0;
}

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

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    font-family: var(--font-mono);
}

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

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.95rem;
    transition: var(--transition);
    position: relative;
}

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

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

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

/* ================================
   Hero Section
   ================================ */

.hero {
    padding: calc(var(--spacing-lg) + 60px) 0 var(--spacing-md) 0;
    min-height: 80vh;
    display: flex;
    align-items: center;
}

.hero-content {
    max-width: 800px;
}

.hero-title {
    font-size: clamp(2.5rem, 8vw, 4.5rem);
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: var(--spacing-sm);
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--text-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(1.1rem, 3vw, 1.5rem);
    color: var(--accent);
    margin-bottom: var(--spacing-md);
    font-weight: 500;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-md);
    max-width: 700px;
}

.hero-social {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.hero-social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: var(--bg-secondary);
    border: 1px solid var(--border);
    color: var(--text-secondary);
    transition: var(--transition);
}

.hero-social-link:hover {
    background-color: var(--bg-tertiary);
    border-color: var(--accent);
    color: var(--accent);
    transform: translateY(-2px);
}

.hero-cta {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

/* ================================
   Buttons
   ================================ */

.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(59, 130, 246, 0.3);
}

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

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

/* ================================
   Sections
   ================================ */

.section {
    padding: var(--spacing-lg) 0;
}

.section-alt {
    background-color: var(--bg-secondary);
}

.section-title {
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

/* ================================
   About Section
   ================================ */

.about-content {
    display: grid;
    grid-template-columns: 200px 1fr;
    gap: var(--spacing-lg);
    align-items: start;
}

.profile-img {
    width: 100%;
    border-radius: 12px;
    border: 1px solid var(--border);
}

.about-text p {
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
    font-size: 1.05rem;
    line-height: 1.8;
}

.about-text strong {
    color: var(--text-primary);
}

/* ================================
   Timeline (Experience)
   ================================ */

.timeline {
    max-width: 800px;
    margin: 0 auto;
}

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

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

.timeline-marker {
    position: absolute;
    left: 0;
    top: 8px;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background-color: var(--accent);
    border: 3px solid var(--bg-secondary);
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: 5px;
    top: 20px;
    bottom: 0;
    width: 2px;
    background-color: var(--border);
}

.timeline-item:last-child::before {
    display: none;
}

.timeline-content h3 {
    font-size: 1.5rem;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.timeline-meta {
    color: var(--text-muted);
    font-size: 0.95rem;
    margin-bottom: var(--spacing-sm);
}

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

/* ================================
   Publications
   ================================ */

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

.publications-intro {
    color: var(--text-secondary);
    font-size: 1.05rem;
}

.scholar-link {
    color: var(--accent);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

.scholar-link:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

.publications-list {
    max-width: 900px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.publication-card {
    background-color: var(--bg-secondary);
    padding: var(--spacing-md);
    border-radius: 8px;
    border: 1px solid var(--border);
    transition: var(--transition);
}

.publication-card:hover {
    border-color: var(--accent);
    transform: translateY(-2px);
}

.publication-card h3 {
    font-size: 1.25rem;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.pub-meta {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-sm);
}

.pub-description {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: var(--spacing-sm);
}

.pub-link {
    display: inline-block;
    color: var(--accent);
    text-decoration: none;
    font-size: 0.95rem;
    transition: var(--transition);
}

.pub-link:hover {
    color: var(--accent-hover);
    text-decoration: underline;
}

/* ================================
   Skills
   ================================ */

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.skill-category h3 {
    font-size: 1.25rem;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

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

.tag {
    display: inline-block;
    padding: 0.5rem 1rem;
    background-color: var(--bg-tertiary);
    color: var(--text-secondary);
    border-radius: 20px;
    font-size: 0.9rem;
    border: 1px solid var(--border);
    transition: var(--transition);
}

.tag:hover {
    background-color: var(--bg-primary);
    color: var(--accent);
    border-color: var(--accent);
}

/* ================================
   Contact Section
   ================================ */

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
    max-width: 1000px;
    margin: 0 auto;
}

.contact-info p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-md);
}

.contact-links {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.contact-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--text-secondary);
    text-decoration: none;
    transition: var(--transition);
}

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

.contact-form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.contact-form input,
.contact-form textarea {
    padding: 0.875rem;
    background-color: var(--bg-secondary);
    border: 1px solid var(--border);
    border-radius: 6px;
    color: var(--text-primary);
    font-family: var(--font-sans);
    font-size: 1rem;
    transition: var(--transition);
}

.contact-form input:focus,
.contact-form textarea:focus {
    outline: none;
    border-color: var(--accent);
}

.contact-form textarea {
    resize: vertical;
    min-height: 120px;
}

/* ================================
   Footer
   ================================ */

.footer {
    background-color: var(--bg-secondary);
    border-top: 1px solid var(--border);
    padding: var(--spacing-md) 0;
    text-align: center;
}

.footer p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.footer-note {
    margin-top: var(--spacing-xs);
}

.footer a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: var(--transition);
}

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

/* ================================
   Responsive Design
   ================================ */

@media (max-width: 768px) {
    .nav-links {
        gap: var(--spacing-sm);
    }
    
    .nav-links a {
        font-size: 0.85rem;
    }
    
    .hero {
        padding-top: calc(var(--spacing-lg) + 60px);
    }
    
    .about-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
        text-align: center;
    }
    
    .profile-img {
        max-width: 200px;
        margin: 0 auto;
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .publications-grid {
        grid-template-columns: 1fr;
    }
    
    .skills-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    :root {
        --spacing-md: 1.5rem;
        --spacing-lg: 3rem;
        --spacing-xl: 4rem;
    }
    
    .hero-cta {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        text-align: center;
    }
}