:root {
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #60a5fa;
    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --text-light: #9ca3af;
    --bg-primary: #23252f;
    --bg-secondary: #272935;
    --bg-dark: #111827;
    --border-color: #374151;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --transition-speed: 0.3s;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    font-size: 16px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Navigation */
#navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(35, 37, 47, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: all var(--transition-speed) ease;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-brand-icon {
    width: 32px;
    height: 32px;
    border-radius: 50%;
}

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

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition-speed) ease;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: width var(--transition-speed) ease;
}

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

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

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    transition: all var(--transition-speed) ease;
}

/* Sections */
.section {
    padding: 80px 0;
    margin-top: 0;
    display: block;
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.section.visible {
    opacity: 1;
    transform: translateY(0);
}

.section:nth-child(even) {
    background-color: #272935;
}

.section:nth-child(odd) {
    background-color: #23252f;
}

.section-title {
    font-size: 2.3rem;
    font-weight: 300;
    margin-bottom: 2rem;
    color: var(--text-primary);
    position: relative;
    display: inline-block;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 0;
    width: 60%;
    height: 4px;
    background: linear-gradient(to right, var(--primary-color), var(--primary-light));
    border-radius: 2px;
}

/* Profile + About Section */
.profile-about-section {
    padding-top: 100px;
    padding-bottom: 80px;
}

.profile-about-grid {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 4rem;
    align-items: start;
}

/* Left: Profile Column */
.profile-column {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

.profile-avatar {
    margin-bottom: 1.5rem;
}

.profile-avatar img {
    width: 270px;
    height: 270px;
    border-radius: 50%;
    object-fit: cover;
    box-shadow: var(--shadow-md);
}

.profile-name {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.profile-role {
    font-size: 1.5rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.profile-org {
    font-size: 1.25rem;
    font-weight: 400;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.profile-links {
    display: flex;
    gap: 1rem;
}

.profile-link {
    color: var(--text-secondary);
    font-size: 1.25rem;
    transition: all var(--transition-speed) ease;
}

.profile-link:hover {
    color: var(--primary-color);
    transform: translateY(-2px);
}

.resume-button {
    margin-top: 1.5rem;
    padding: 0.75rem 1.5rem;
    background: var(--primary-color);
    color: var(--text-primary);
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    font-family: inherit;
    cursor: pointer;
    transition: all var(--transition-speed) ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    width: fit-content;
}

.resume-button:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.resume-button i {
    font-size: 1rem;
}

/* Right: About Column */
.about-column {
    display: flex;
    flex-direction: column;
}

#about-bio {
    color: var(--text-primary);
    line-height: 1.8;
    margin-bottom: 2rem;
}

.interests-education-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

.interests-list, .education-list {
    margin-top: 2rem;
}

.interests-list h3, .education-list h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.interest-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.interest-tag {
    padding: 0.5rem 1rem;
    background: var(--primary-color);
    color: white;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
}

.education-item {
    margin-bottom: 1.5rem;
    padding: 1.5rem;
    background: var(--bg-primary);
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
}

.education-degree {
    font-weight: 600;
    font-size: 1.125rem;
    color: var(--text-primary);
}

.education-institution {
    color: var(--primary-color);
    font-weight: 500;
}

.education-year {
    color: var(--text-light);
    font-size: 0.9rem;
}

/* Timeline */
.timeline {
    position: relative;
    padding-left: 3rem;
}

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

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
    padding: 1.5rem;
    background: rgba(255, 255, 255, 0.03);
    border-radius: 8px;
    border-left: 3px solid var(--primary-color);
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -3.4rem;
    top: 1.5rem;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--primary-color);
    border: 3px solid #23252f;
}

.timeline-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 0.5rem;
}

.timeline-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
}

.timeline-company {
    font-size: 1.125rem;
    color: var(--primary-color);
    font-weight: 500;
}

.timeline-date {
    color: var(--text-light);
    font-size: 0.9rem;
    white-space: nowrap;
}

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

.timeline-description ul {
    margin-top: 0.5rem;
    padding-left: 1.5rem;
}

.timeline-description li {
    margin-bottom: 0.5rem;
}

/* Projects Grid */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
}

.project-card {
    background: rgba(255, 255, 255, 0.03);
    border-radius: 8px;
    overflow: hidden;
    border: 1px solid var(--border-color);
    transition: all var(--transition-speed) ease;
    cursor: pointer;
    text-decoration: none;
    color: inherit;
    display: block;
}

.project-card:hover {
    transform: translateY(-3px);
    border-color: var(--primary-color);
    box-shadow: 0 4px 12px rgba(37, 99, 235, 0.2);
}

.project-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.project-content {
    padding: 1.5rem;
}

.project-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.project-description {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.6;
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.project-tag {
    padding: 0.25rem 0.75rem;
    background: var(--bg-secondary);
    border-radius: 12px;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Publications */
.publications-intro {
    margin-bottom: 2rem;
    font-size: 1.125rem;
}

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

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

.publications-filter {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.5rem 1.5rem;
    background: var(--bg-secondary);
    border: 2px solid transparent;
    border-radius: 20px;
    cursor: pointer;
    font-weight: 500;
    color: var(--text-secondary);
    transition: all var(--transition-speed) ease;
}

.filter-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

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

.publications-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.publication-item {
    background: var(--bg-primary);
    padding: 1.25rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-speed) ease;
}

.publication-item:hover {
    box-shadow: var(--shadow-md);
}

.publication-item.hidden {
    display: none;
}

.show-more-button {
    margin-top: 2rem;
    padding: 0.75rem 2rem;
    background: var(--bg-secondary);
    color: var(--text-primary);
    border: 2px solid var(--primary-color);
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    font-family: inherit;
    cursor: pointer;
    transition: all var(--transition-speed) ease;
    display: block;
    margin-left: auto;
    margin-right: auto;
}

.show-more-button:hover {
    background: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.show-more-button.hidden {
    display: none;
}

.publication-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.publication-title a {
    color: var(--text-primary);
    text-decoration: none;
    transition: color var(--transition-speed) ease;
}

.publication-title a:hover {
    color: var(--primary-color);
}

.publication-authors {
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.publication-venue {
    color: var(--primary-color);
    font-style: italic;
    margin-bottom: 1rem;
}

.publication-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.publication-link {
    padding: 0.5rem 1rem;
    background: var(--bg-secondary);
    border-radius: 6px;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    transition: all var(--transition-speed) ease;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.publication-link:hover {
    background: var(--primary-color);
    color: white;
}

/* Contact Section */
.contact-content {
    text-align: center;
    max-width: 600px;
    margin: 0 auto;
}

.contact-content p {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.contact-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
}

.contact-link {
    color: var(--text-secondary);
    
    .nav-toggle {
        display: flex;
    }
    
    .profile-content {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2rem;
    }
    
    .profile-avatar {
        order: -1;
        display: flex;
        justify-content: center;
    }
    
    .profile-avatar img {
        width: 200px;
        height: 200px;
    }
    
    .profile-name {
        font-size: 2rem;
    }
    
    .profile-role {
        font-size: 1.25rem;
    }
    
    .profile-org {
        font-size: 1.1rem;
    }
    
    .profile-links {
        justify-content: center;
    }
    
    .section {
        padding: 3rem 0;
        min-height: auto;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .timeline {
        padding-left: 2rem;
    }
}

/* Utility classes */
.hidden {
    display: none !important;
}

.fade-in {
    animation: fadeIn 0.6s ease-in;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}