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

:root {
    --primary-color: #2563eb;
    --primary-dark: #1d4ed8;
    --secondary-color: #64748b;
    --accent-color: #06b6d4;
    --bg-color: #f8fafc;
    --white: #ffffff;
    --text-dark: #1e293b;
    --text-light: #64748b;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    --sidebar-width: 350px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-color);
    overflow-x: hidden;
}

/* Sidebar Styles */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: var(--sidebar-width);
    height: 100vh;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--white);
    overflow-y: auto;
    z-index: 1000;
    transition: var(--transition);
}

.sidebar-content {
    padding: 2rem 1.5rem;
}

.profile-section {
    text-align: center;
    margin-bottom: 2rem;
}

.profile-image {
    width: 150px;
    height: 150px;
    margin: 0 auto 1.5rem;
    border-radius: 50%;
    overflow: hidden;
    border: 4px solid rgba(255, 255, 255, 0.2);
    transition: var(--transition);
}

.profile-image:hover {
    transform: scale(1.05);
    border-color: rgba(255, 255, 255, 0.4);
}

.profile-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
}

.name {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.title {
    font-size: 1rem;
    opacity: 0.9;
    margin-bottom: 0.25rem;
}

.affiliation {
    font-size: 0.875rem;
    opacity: 0.8;
}

/* Navigation */
.navigation {
    margin-bottom: 2rem;
}

.navigation ul {
    list-style: none;
}

.navigation li {
    margin-bottom: 0.5rem;
}

.nav-link {
    display: flex;
    align-items: center;
    padding: 0.75rem 1rem;
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    border-radius: 0.5rem;
    transition: var(--transition);
    font-weight: 500;
}

.nav-link:hover {
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--white);
}

.nav-link.active {
    background-color: rgba(255, 255, 255, 0.15);
    color: var(--white);
}

.nav-link i {
    margin-right: 0.75rem;
    width: 1.25rem;
}

/* Contact Section */
.contact-section {
    margin-bottom: 2rem;
    padding-top: 1rem;
    border-top: 1px solid rgba(255, 255, 255, 0.2);
}

.contact-section h3 {
    font-size: 1rem;
    margin-bottom: 1rem;
    opacity: 0.9;
}

.contact-item {
    display: flex;
    align-items: center;
    margin-bottom: 0.75rem;
    font-size: 0.875rem;
}

.contact-item i {
    margin-right: 0.75rem;
    width: 1rem;
    opacity: 0.8;
}

.contact-item a {
    color: rgba(255, 255, 255, 0.9);
    text-decoration: none;
    transition: var(--transition);
}

.contact-item a:hover {
    color: var(--white);
}

/* Social Links */
.social-links {
    display: flex;
    gap: 1rem;
    justify-content: center;
    padding-top: 1rem;
    border-top: 1px solid rgba(255, 255, 255, 0.2);
}

.social-links a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 2.5rem;
    height: 2.5rem;
    background-color: rgba(255, 255, 255, 0.1);
    border-radius: 50%;
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: var(--transition);
}

.social-links a:hover {
    background-color: rgba(255, 255, 255, 0.2);
    color: var(--white);
    transform: translateY(-2px);
}

/* Main Content */
.main-content {
    margin-left: var(--sidebar-width);
    padding: 2rem 3rem;
    min-height: 100vh;
}

/* Page Styles */
.page {
    display: none;
    animation: fadeIn 0.5s ease-in-out;
}

.page.active {
    display: block;
}

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

.page-header {
    margin-bottom: 3rem;
}

.page-header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.header-line {
    width: 60px;
    height: 4px;
    background: linear-gradient(to right, var(--primary-color), var(--accent-color));
    border-radius: 2px;
}

/* Home Page Styles */
.content-grid {
    display: grid;
    gap: 3rem;
    max-width: 1200px;
}

.intro-section .lead {
    font-size: 1.25rem;
    line-height: 1.7;
    color: var(--text-light);
    margin-bottom: 2rem;
}

.highlight-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.card {
    background: var(--white);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
    border: 1px solid var(--border-color);
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.card-icon {
    width: 3rem;
    height: 3rem;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 0.75rem;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1rem;
}

.card-icon i {
    color: var(--white);
    font-size: 1.25rem;
}

.card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

.card p {
    color: var(--text-light);
    line-height: 1.6;
}

/* Research Interests */
.interests-grid {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 2rem;
}

.interest-tag {
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    color: var(--white);
    padding: 0.5rem 1rem;
    border-radius: 2rem;
    font-size: 0.875rem;
    font-weight: 500;
}

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

.timeline::before {
    content: '';
    position: absolute;
    left: 0.75rem;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--border-color);
}

.timeline-item {
    position: relative;
    margin-bottom: 2rem;
}

.timeline-marker {
    position: absolute;
    left: -2rem;
    top: 0.25rem;
    width: 1rem;
    height: 1rem;
    background: var(--primary-color);
    border-radius: 50%;
    border: 3px solid var(--white);
    box-shadow: var(--shadow-sm);
}

.timeline-content h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.timeline-meta {
    color: var(--text-light);
    font-size: 0.875rem;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

/* Publications Page */
.section-intro {
    font-size: 1.125rem;
    color: var(--text-light);
    margin-bottom: 2rem;
    line-height: 1.7;
}

.publications-grid {
    display: grid;
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.publication-item {
    background: var(--white);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: var(--transition);
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 1.5rem;
    cursor: pointer;
}

.publication-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

.publication-header h3 {
    margin-bottom: 0;
}

.expand-icon {
    color: var(--primary-color);
    transition: var(--transition);
    font-size: 1.2rem;
}

.publication-item.expanded .expand-icon {
    transform: rotate(180deg);
}

.publication-abstract {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease-out;
    margin-bottom: 0;
}

.publication-item.expanded .publication-abstract {
    max-height: 200px;
    margin-bottom: 1rem;
}

.publication-abstract p {
    color: var(--text-dark);
    line-height: 1.6;
    margin: 0;
    padding: 1rem 0;
    border-top: 1px solid var(--border-color);
}

.publication-year {
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    opacity: 0.7;
}

.publication-content h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

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

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

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

.link-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    padding: 0.375rem 0.75rem;
    background: var(--bg-color);
    color: var(--primary-color);
    text-decoration: none;
    border-radius: 0.375rem;
    font-size: 0.875rem;
    font-weight: 500;
    transition: var(--transition);
}

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



/* Topics Page */
.topic-categories {
    margin-bottom: 2rem;
}

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

.category-btn {
    padding: 0.5rem 1rem;
    border: 2px solid var(--border-color);
    background: var(--white);
    color: var(--text-light);
    border-radius: 2rem;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
}

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

.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.topic-card {
    background: var(--white);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

.topic-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.topic-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.topic-level {
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
}

.topic-level.masters {
    background: var(--primary-color);
    color: var(--white);
}

.topic-level.bachelors {
    background: var(--accent-color);
    color: var(--white);
}

.topic-level.intern {
    background: #10b981;
    color: var(--white);
}

.topic-status {
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
}

.topic-status.available {
    background: #10b981;
    color: var(--white);
}

.topic-status.taken {
    background: #ef4444;
    color: var(--white);
}

.topic-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

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

.topic-skills {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.skill-tag {
    background: var(--bg-color);
    color: var(--text-dark);
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 500;
}

.topic-details {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    font-size: 0.875rem;
    color: var(--text-light);
}

.detail-item {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.contact-btn {
    width: 100%;
    padding: 0.75rem;
    background: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: 0.5rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

.contact-btn:hover:not(:disabled) {
    background: var(--primary-dark);
}

.contact-btn:disabled {
    background: var(--secondary-color);
    cursor: not-allowed;
}

/* Application Info */
.application-info {
    background: var(--white);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

.application-steps {
    display: grid;
    gap: 2rem;
    margin-top: 1.5rem;
}

.step {
    display: flex;
    gap: 1rem;
    align-items: flex-start;
}

.step-number {
    width: 2.5rem;
    height: 2.5rem;
    background: var(--primary-color);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    flex-shrink: 0;
}

.step-content h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.step-content p {
    color: var(--text-light);
    line-height: 1.6;
}

/* Mobile Menu */
.mobile-menu-toggle {
    display: none;
    position: fixed;
    top: 1rem;
    left: 1rem;
    z-index: 1100;
    background: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: 0.5rem;
    width: 3rem;
    height: 3rem;
    cursor: pointer;
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
}

.mobile-menu-toggle:hover {
    background: var(--primary-dark);
}

/* Responsive Design */
@media (max-width: 1024px) {
    :root {
        --sidebar-width: 300px;
    }
    
    .main-content {
        padding: 2rem;
    }
    
    .topics-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .mobile-menu-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
    }
    
    .sidebar {
        transform: translateX(-100%);
    }
    
    .sidebar.active {
        transform: translateX(0);
    }
    
    .main-content {
        margin-left: 0;
        padding: 4rem 1.5rem 2rem;
    }
    
    .page-header h1 {
        font-size: 2rem;
    }
    
    .highlight-cards {
        grid-template-columns: 1fr;
    }
    
    .publication-item {
        grid-template-columns: 1fr;
        gap: 1rem;
    }
    
    .publication-year {
        text-align: center;
        font-size: 1.5rem;
    }
    
    .topics-grid {
        grid-template-columns: 1fr;
    }
    
    .topic-card {
        min-width: unset;
    }
}

@media (max-width: 480px) {
    .main-content {
        padding: 4rem 1rem 2rem;
    }
    
    .sidebar-content {
        padding: 1.5rem 1rem;
    }
    
    .profile-image {
        width: 120px;
        height: 120px;
    }
    
    .name {
        font-size: 1.25rem;
    }
    
    .social-links {
        gap: 0.75rem;
    }
    
    .social-links a {
        width: 2rem;
        height: 2rem;
    }
    
    .application-steps {
        gap: 1.5rem;
    }
    
    .step {
        flex-direction: column;
        text-align: center;
    }
}

/* Print Styles */
@media print {
    .sidebar,
    .mobile-menu-toggle {
        display: none;
    }
    
    .main-content {
        margin-left: 0;
        padding: 0;
    }
    
    .page {
        display: block !important;
        page-break-after: always;
    }
    
    .page:last-child {
        page-break-after: avoid;
    }
}