/* CSS Variables for Dark Mode */
:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #f3f4f6;
    --text-primary: #333;
    --text-secondary: #6b7280;
    --text-muted: #9ca3af;
    --border-color: #e5e7eb;
    --shadow-light: rgba(0, 0, 0, 0.05);
    --shadow-medium: rgba(0, 0, 0, 0.1);
    --accent-color: #6366f1;
    --accent-hover: #4f46e5;
    --success-color: #10b981;
    --danger-color: #ef4444;
}

[data-theme="dark"] {
    --bg-primary: #1f2937;
    --bg-secondary: #111827;
    --bg-tertiary: #374151;
    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --text-muted: #9ca3af;
    --border-color: #374151;
    --shadow-light: rgba(0, 0, 0, 0.3);
    --shadow-medium: rgba(0, 0, 0, 0.5);
    --accent-color: #8b5cf6;
    --accent-hover: #7c3aed;
    --success-color: #34d399;
    --danger-color: #f87171;
}

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

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    overflow-x: hidden;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    padding: 1rem 0;
    transition: all 0.3s ease;
    border-bottom: 1px solid var(--border-color);
}

[data-theme="dark"] .navbar {
    background: rgba(31, 41, 55, 0.95);
    border-bottom: 1px solid var(--border-color);
}

[data-theme="dark"] .nav-link {
    color: var(--text-primary);
}

[data-theme="dark"] .nav-link:hover {
    color: var(--accent-color);
}

[data-theme="dark"] .bar {
    background: var(--text-primary);
}

[data-theme="dark"] .nav-logo h2 {
    color: var(--accent-color);
}

[data-theme="dark"] .hamburger {
    color: var(--text-primary);
}

.nav-controls {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.theme-toggle {
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.2rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 8px;
    transition: all 0.3s ease;
}

.theme-toggle:hover {
    background: var(--bg-tertiary);
    color: var(--accent-color);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo h2 {
    color: #6366f1;
    font-weight: 700;
    font-size: 1.8rem;
    font-family: 'Courier New', monospace;
}

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

.nav-link {
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
}

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-color);
    transition: width 0.3s ease;
}

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

.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

.bar {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    margin: 3px 0;
    transition: 0.3s;
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, #1e3c72 0%, #2a5298 50%, #667eea 100%);
    color: white;
    padding-top: 80px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><pattern id="grid" width="10" height="10" patternUnits="userSpaceOnUse"><path d="M 10 0 L 0 0 0 10" fill="none" stroke="rgba(255,255,255,0.1)" stroke-width="0.5"/></pattern></defs><rect width="100" height="100" fill="url(%23grid)"/></svg>');
    opacity: 0.3;
}

.hero-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
    position: relative;
    z-index: 2;
}

.hero-title::before {
    content: '> ';
    color: #10b981;
    font-family: 'Courier New', monospace;
}

.hero-subtitle {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    opacity: 0.9;
    position: relative;
    z-index: 2;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    position: relative;
    z-index: 2;
}

.btn {
    padding: 12px 30px;
    border: none;
    border-radius: 50px;
    font-weight: 600;
    text-decoration: none;
    display: inline-block;
    transition: all 0.3s ease;
    cursor: pointer;
    font-size: 1rem;
}

.btn-primary {
    background: #6366f1;
    color: white;
}

.btn-primary:hover {
    background: #4f46e5;
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(99, 102, 241, 0.3);
}

.btn-secondary {
    background: transparent;
    color: white;
    border: 2px solid white;
}

.btn-secondary:hover {
    background: white;
    color: #6366f1;
    transform: translateY(-2px);
}

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    z-index: 2;
}

.image-placeholder {
    width: 300px;
    height: 300px;
    background: rgba(255, 255, 255, 0.1);
    border: 2px dashed rgba(255, 255, 255, 0.3);
    border-radius: 20px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    color: white;
    font-size: 3rem;
    transition: all 0.3s ease;
    backdrop-filter: blur(10px);
}

.image-placeholder:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: scale(1.05);
}

.image-placeholder p {
    font-size: 1rem;
    margin-top: 1rem;
    text-align: center;
}

.image-placeholder img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
}

.image-placeholder img:hover {
    transform: scale(1.05);
}

/* Hide the placeholder icon and text when image is present */
.image-placeholder:has(img) i,
.image-placeholder:has(img) p {
    display: none;
}

/* Section Styles */
.section-title {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

/* About Section */
.about {
    padding: 5rem 0;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-tertiary) 100%);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
    align-items: center;
}

.about-text h3 {
    font-size: 2rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.about-text p {
    font-size: 1.1rem;
    margin-bottom: 2rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

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

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

.skill-name {
    font-weight: 600;
    color: var(--text-primary);
}

.skill-bar {
    width: 100%;
    height: 8px;
    background: var(--bg-tertiary);
    border-radius: 4px;
    overflow: hidden;
}

.skill-progress {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-color), var(--accent-hover));
    border-radius: 4px;
    transition: width 1s ease;
}

.about-image {
    display: flex;
    justify-content: center;
}

.about-image .image-placeholder {
    width: 250px;
    height: 250px;
    background: linear-gradient(135deg, var(--accent-color) 0%, var(--accent-hover) 100%);
    border: none;
    color: white;
    box-shadow: 0 10px 30px var(--shadow-medium);
}

/* Portfolio Section */
.portfolio {
    padding: 5rem 0;
    background: var(--bg-primary);
}

.portfolio-filters {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 10px 20px;
    border: 2px solid var(--accent-color);
    background: transparent;
    color: var(--accent-color);
    border-radius: 25px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
}

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

.portfolio-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.portfolio-item {
    position: relative;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    transition: all 0.3s ease;
}

.portfolio-item:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.15);
}

.portfolio-image {
    height: 250px;
    overflow: hidden;
}

.portfolio-image .image-placeholder {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #1e3c72 0%, #2a5298 50%, #667eea 100%);
    border: none;
    font-size: 2rem;
    position: relative;
}

.portfolio-image .image-placeholder::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><pattern id="grid" width="10" height="10" patternUnits="userSpaceOnUse"><path d="M 10 0 L 0 0 0 10" fill="none" stroke="rgba(255,255,255,0.1)" stroke-width="0.5"/></pattern></defs><rect width="100" height="100" fill="url(%23grid)"/></svg>');
    opacity: 0.3;
}

.portfolio-overlay {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    background: linear-gradient(transparent, rgba(0, 0, 0, 0.8));
    color: white;
    padding: 2rem;
    transform: translateY(100%);
    transition: transform 0.3s ease;
}

.portfolio-item:hover .portfolio-overlay {
    transform: translateY(0);
}

.portfolio-overlay h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.portfolio-overlay p {
    opacity: 0.9;
}

/* Blog Section */
.blog {
    padding: 5rem 0;
    background: var(--bg-primary);
}

.section-subtitle {
    text-align: center;
    font-size: 1.1rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.blog-filters {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.blog-item {
    background: var(--bg-primary);
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 10px 30px var(--shadow-medium);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
}

.blog-item:hover {
    transform: translateY(-10px);
    box-shadow: 0 20px 40px var(--shadow-medium);
}

.blog-image {
    height: 200px;
    overflow: hidden;
    position: relative;
}

.blog-image .image-placeholder {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #1e3c72 0%, #2a5298 50%, #667eea 100%);
    border: none;
    font-size: 2rem;
    position: relative;
}

.blog-content {
    padding: 1.5rem;
}

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

.blog-category {
    background: var(--accent-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 600;
}

.blog-date {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.blog-title {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
    line-height: 1.4;
}

.blog-excerpt {
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 1.5rem;
    font-size: 0.95rem;
}

.blog-stats {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.blog-stats span {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.blog-stats i {
    color: var(--accent-color);
}

.blog-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    transition: color 0.3s ease;
}

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

.blog-cta {
    text-align: center;
    margin-top: 3rem;
}

/* Research Section */
.research {
    padding: 5rem 0;
    background: linear-gradient(135deg, #1e293b 0%, #334155 100%);
    color: white;
}

.research .section-title,
.research .section-subtitle {
    color: white;
}

.research-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
    margin-bottom: 3rem;
}

.research-item {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 15px;
    overflow: hidden;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    transition: all 0.3s ease;
}

.research-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.3);
}

.research-item.featured {
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.2) 0%, rgba(139, 92, 246, 0.2) 100%);
    border: 2px solid rgba(99, 102, 241, 0.5);
}

.research-image {
    height: 250px;
    position: relative;
    overflow: hidden;
}

.research-image .image-placeholder {
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    border: none;
    font-size: 2.5rem;
    position: relative;
}

.research-badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: #f59e0b;
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.research-content {
    padding: 2rem;
}

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

.research-category {
    background: rgba(99, 102, 241, 0.3);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 600;
}

.research-date {
    color: rgba(255, 255, 255, 0.7);
    font-size: 0.9rem;
}

.research-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: white;
    line-height: 1.4;
}

.research-excerpt {
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.6;
    margin-bottom: 1.5rem;
    font-size: 0.95rem;
}

.research-details {
    margin-bottom: 2rem;
}

.research-tech h4 {
    color: white;
    font-size: 1rem;
    margin-bottom: 1rem;
}

.tech-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.tech-tag {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 500;
    border: 1px solid rgba(255, 255, 255, 0.3);
}

.research-metrics {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
}

.metric {
    text-align: center;
    padding: 1rem;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 10px;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.metric-value {
    display: block;
    font-size: 1.5rem;
    font-weight: 700;
    color: #10b981;
    margin-bottom: 0.25rem;
}

.metric-label {
    font-size: 0.8rem;
    color: rgba(255, 255, 255, 0.7);
}

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

.research-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: #10b981;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    padding: 0.5rem 1rem;
    border: 1px solid rgba(16, 185, 129, 0.3);
    border-radius: 8px;
    transition: all 0.3s ease;
}

.research-link:hover {
    background: rgba(16, 185, 129, 0.1);
    color: #10b981;
    transform: translateY(-2px);
}

.research-sidebar {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.research-sidebar .research-item {
    background: rgba(255, 255, 255, 0.05);
}

.research-sidebar .research-image {
    height: 150px;
}

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

.research-sidebar .research-title {
    font-size: 1.2rem;
}

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

/* Paper Modal */
.paper-modal {
    display: none;
    position: fixed;
    z-index: 2000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(5px);
}

.paper-modal-content {
    background: white;
    margin: 2% auto;
    padding: 0;
    border-radius: 15px;
    width: 90%;
    max-width: 900px;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.paper-modal-header {
    background: linear-gradient(135deg, #1e293b 0%, #334155 100%);
    color: white;
    padding: 2rem;
    border-radius: 15px 15px 0 0;
    position: sticky;
    top: 0;
    z-index: 10;
}

.paper-modal-header h2 {
    margin: 0;
    font-size: 1.8rem;
    font-weight: 600;
}

.close-modal {
    position: absolute;
    top: 1.5rem;
    right: 2rem;
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 50%;
    transition: background-color 0.3s ease;
}

.close-modal:hover {
    background: rgba(255, 255, 255, 0.1);
}

.paper-modal-body {
    padding: 2rem;
    background: white;
    color: #333;
}

.paper-info {
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid #e2e8f0;
}

.paper-meta {
    display: flex;
    gap: 2rem;
    flex-wrap: wrap;
    font-size: 0.9rem;
    color: #666;
}

.paper-meta span {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.paper-content {
    line-height: 1.8;
    font-size: 1rem;
}

.paper-content h3 {
    color: #1e293b;
    font-size: 1.5rem;
    font-weight: 600;
    margin: 2rem 0 1rem 0;
    padding-bottom: 0.5rem;
    border-bottom: 2px solid #6366f1;
}

.paper-content h3:first-child {
    margin-top: 0;
}

.paper-content h4 {
    color: #334155;
    font-size: 1.2rem;
    font-weight: 600;
    margin: 1.5rem 0 1rem 0;
}

.paper-content p {
    margin-bottom: 1rem;
    text-align: justify;
}

.paper-content ol {
    margin: 1rem 0;
    padding-left: 2rem;
}

.paper-content li {
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

/* Modal scrollbar styling */
.paper-modal-content::-webkit-scrollbar {
    width: 8px;
}

.paper-modal-content::-webkit-scrollbar-track {
    background: #f1f5f9;
    border-radius: 4px;
}

.paper-modal-content::-webkit-scrollbar-thumb {
    background: #6366f1;
    border-radius: 4px;
}

.paper-modal-content::-webkit-scrollbar-thumb:hover {
    background: #4f46e5;
}

/* Certificates Section */
.certificates {
    padding: 5rem 0;
    background: var(--bg-primary);
}

.certificates-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.certificate-item {
    background: var(--bg-primary);
    border-radius: 15px;
    box-shadow: 0 10px 30px var(--shadow-light);
    display: flex;
    align-items: center;
    gap: 1.5rem;
    padding: 2rem;
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
}

.certificate-item:hover {
    transform: translateY(-5px) scale(1.02);
    box-shadow: 0 20px 40px var(--shadow-medium);
    border-color: var(--accent-color);
}

.certificate-icon {
    font-size: 2.5rem;
    color: var(--accent-color);
    flex-shrink: 0;
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--bg-tertiary) 0%, var(--bg-secondary) 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

.certificate-item:hover .certificate-icon {
    background: linear-gradient(135deg, var(--accent-color) 0%, var(--accent-hover) 100%);
    color: white;
    transform: scale(1.1);
}

.certificate-content {
    flex: 1;
}

.certificate-content h3 {
    margin: 0 0 0.5rem 0;
    font-size: 1.2rem;
    color: var(--text-primary);
    font-weight: 600;
    line-height: 1.3;
}

.certificate-content p {
    margin: 0 0 0.5rem 0;
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.4;
}

.certificate-date {
    display: inline-block;
    background: var(--bg-tertiary);
    color: var(--accent-color);
    border-radius: 8px;
    padding: 0.2rem 0.7rem;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.8rem;
}

.certificate-link {
    display: inline-flex;
    align-items: center;
    gap: 0.3rem;
    color: var(--accent-color);
    font-weight: 600;
    text-decoration: none;
    font-size: 0.9rem;
    transition: all 0.3s ease;
    padding: 0.3rem 0;
}

.certificate-link:hover {
    color: var(--accent-hover);
    transform: translateX(3px);
}

.certificate-link i {
    font-size: 0.8rem;
}

.certificates-cta {
    text-align: center;
    margin-top: 3rem;
}

/* Contact Section */
.contact {
    padding: 5rem 0;
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 4rem;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1.5rem;
    background: white;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease;
}

.contact-item:hover {
    transform: translateY(-5px);
}

.contact-item i {
    font-size: 1.5rem;
    color: #6366f1;
    width: 50px;
    height: 50px;
    background: #f1f5f9;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}

.contact-item h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: #333;
}

.contact-item p {
    color: #666;
}

.contact-email {
    color: #666;
    text-decoration: none;
    transition: color 0.3s ease;
}

.contact-email:hover {
    color: #3b82f6;
    text-decoration: underline;
}

.contact-link {
    color: #666;
    text-decoration: none;
    transition: color 0.3s ease;
}

.contact-link:hover {
    color: #3b82f6;
    text-decoration: underline;
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 15px;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    font-size: 1rem;
    transition: border-color 0.3s ease;
    font-family: inherit;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: #6366f1;
}

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

/* Footer */
.footer {
    background: var(--bg-primary);
    color: var(--text-primary);
    padding: 3rem 0 1rem;
    border-top: 1px solid var(--border-color);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-column {
    display: flex;
    flex-direction: column;
}

.footer-heading {
    color: var(--accent-color);
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.footer-info {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.footer-info-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.footer-info-item i {
    color: var(--text-secondary);
    width: 16px;
}

.email-link {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

.phone-link {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

.footer-info p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.5;
    margin-bottom: 0.5rem;
}

.footer-social {
    display: flex;
    gap: 1rem;
}

.social-icon {
    width: 40px;
    height: 40px;
    border: 1px solid var(--text-primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-primary);
    text-decoration: none;
    transition: all 0.3s ease;
    background: var(--bg-primary);
}

.social-icon:hover {
    background: var(--bg-tertiary);
    transform: translateY(-2px);
}

.response-time {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.response-highlight {
    color: var(--success-color);
    font-weight: 500;
}

.footer-separator {
    height: 1px;
    background: var(--border-color);
    margin: 2rem 0;
}

.footer-copyright {
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--bg-primary);
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: 0 10px 27px var(--shadow-light);
        padding: 2rem 0;
    }

    .nav-menu.active {
        left: 0;
    }

    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 2rem;
    }



    .hero-title {
        font-size: 2.5rem;
    }

    .hero-buttons {
        justify-content: center;
    }

    .about-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .contact-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .footer-content {
        grid-template-columns: 1fr;
        gap: 2rem;
        text-align: center;
    }
    
    .footer-social {
        justify-content: center;
    }

    .portfolio-filters,
    .blog-filters {
        gap: 0.5rem;
    }

    .filter-btn {
        padding: 8px 16px;
        font-size: 0.9rem;
    }

    .blog-grid {
        grid-template-columns: 1fr;
    }

    .research-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

    .research-metrics {
        grid-template-columns: repeat(2, 1fr);
    }

    .research-links {
        flex-direction: column;
    }

    .paper-modal-content {
        width: 95%;
        margin: 1% auto;
    }

    .paper-modal-header {
        padding: 1.5rem;
    }

    .paper-modal-header h2 {
        font-size: 1.5rem;
    }

    .paper-modal-body {
        padding: 1.5rem;
    }

    .paper-meta {
        flex-direction: column;
        gap: 1rem;
    }

    .certificates-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .certificate-item {
        padding: 1.5rem;
        gap: 1rem;
    }

    .certificate-icon {
        width: 50px;
        height: 50px;
        font-size: 2rem;
    }

    .experience-header {
        flex-direction: column;
        gap: 1rem;
    }

    .experience-actions {
        align-self: flex-end;
    }

    .company-details {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.25rem;
    }

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

    .education-item {
        padding: 1.5rem;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }

    .section-title {
        font-size: 2rem;
    }

    .portfolio-grid {
        grid-template-columns: 1fr;
    }

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 200px;
        text-align: center;
    }
}

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

.hero-content,
.about-content,
.portfolio-grid,
.contact-content {
    animation: fadeInUp 0.8s ease-out;
}

/* Smooth scrolling */
html {
    scroll-behavior: smooth;
} 

/* Experience Section */
.experience {
    padding: 5rem 0;
    background: var(--bg-secondary);
}

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

.experience-item {
    background: var(--bg-primary);
    border-radius: 12px;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 4px 6px var(--shadow-light);
    border: 1px solid var(--border-color);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.experience-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px var(--shadow-medium);
}

.experience-header {
    display: flex;
    align-items: flex-start;
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.experience-logo {
    flex-shrink: 0;
}

.company-logo {
    width: 60px;
    height: 60px;
    background: #3b82f6;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 600;
    font-size: 1.2rem;
}

.experience-info {
    flex: 1;
}

.job-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: #1f2937;
    margin-bottom: 0.5rem;
}

.company-details {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
    flex-wrap: wrap;
}

.company-name {
    color: #6b7280;
    font-size: 0.95rem;
}

.role-type {
    color: #10b981;
    font-weight: 500;
    font-size: 0.9rem;
}

.experience-duration {
    color: #9ca3af;
    font-size: 0.9rem;
}

.experience-actions {
    display: flex;
    gap: 0.5rem;
    flex-shrink: 0;
}

.action-btn {
    width: 36px;
    height: 36px;
    border: 1px solid #d1d5db;
    border-radius: 8px;
    background: white;
    color: #6b7280;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s ease;
}

.action-btn:hover {
    background: #f3f4f6;
    color: #374151;
    border-color: #9ca3af;
}

.experience-description {
    color: #4b5563;
    line-height: 1.6;
}

.experience-description p {
    margin-bottom: 1rem;
}

.experience-skills {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.skill-tag {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    background: #f3f4f6;
    color: #374151;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
}

.skill-tag i {
    color: #8b5cf6;
    font-size: 0.8rem;
} 

/* Education Section */
.education {
    padding: 5rem 0;
    background: var(--bg-primary);
}

.education-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 3rem;
    max-width: 1000px;
    margin: 0 auto;
}

.education-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: 2rem;
    border-radius: 12px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.education-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px var(--shadow-medium);
}

.education-period {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
    align-self: flex-start;
}

.period-bullet {
    color: var(--text-primary);
    font-weight: bold;
}

.education-logo {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 1rem;
}

.logo-circle {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background: var(--bg-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 0.5rem;
    box-shadow: 0 4px 6px var(--shadow-light);
    border: 2px solid var(--border-color);
}

.logo-circle.blue {
    background: #3b82f6;
    color: white;
}

.logo-content {
    font-size: 2rem;
    color: var(--accent-color);
}

.logo-circle.blue .logo-content {
    color: white;
}

.institution-name {
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-weight: 500;
    text-align: center;
    max-width: 120px;
}

.education-category {
    margin-bottom: 1rem;
}

.education-category span {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

.education-details {
    text-align: center;
}

.degree-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.degree-title i {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.institution {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.education-description {
    color: var(--text-secondary);
    font-size: 0.85rem;
    line-height: 1.5;
    text-align: center;
}

.education-location {
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-bottom: 0.5rem;
}

.education-grade {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 0.5rem;
}

.grade-label {
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 500;
}

.grade-value {
    color: var(--success-color);
    font-size: 0.9rem;
    font-weight: 600;
    background: var(--bg-tertiary);
    padding: 0.25rem 0.5rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
}