/* ===== CSS VARIABLES ===== */
:root {
    /* Light Theme Colors */
    --primary-color: #4a90e2;
    --secondary-color: #50c878;
    --accent-color: #ff6b35;
    --text-primary: #2c3e50;
    --text-secondary: #7f8c8d;
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --border-color: #dee2e6;
    --shadow-light: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-medium: 0 4px 20px rgba(0, 0, 0, 0.15);
    --shadow-heavy: 0 8px 30px rgba(0, 0, 0, 0.2);
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-heading: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    --spacing-3xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.25rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* Dark Theme Colors */
[data-theme="dark"] {
    --primary-color: #64b5f6;
    --secondary-color: #66bb6a;
    --accent-color: #ff8a65;
    --text-primary: #f1f1f1;
    --text-secondary: #b0b0b0;
    --bg-primary: #1a1a1a;
    --bg-secondary: #2c2c2c;
    --bg-tertiary: #3a3a3a;
    --border-color: #404040;
    --shadow-light: 0 2px 10px rgba(0, 0, 0, 0.3);
    --shadow-medium: 0 4px 20px rgba(0, 0, 0, 0.4);
    --shadow-heavy: 0 8px 30px rgba(0, 0, 0, 0.5);
}

/* Light Theme Colors (explicit) */
.light-mode {
    --primary-color: #4a90e2;
    --secondary-color: #50c878;
    --accent-color: #ff6b35;
    --text-primary: #2c3e50;
    --text-secondary: #7f8c8d;
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --border-color: #dee2e6;
    --shadow-light: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-medium: 0 4px 20px rgba(0, 0, 0, 0.15);
    --shadow-heavy: 0 8px 30px rgba(0, 0, 0, 0.2);
}

/* ===== GLOBAL STYLES ===== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* ===== TYPOGRAPHY ===== */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 600;
    line-height: 1.2;
    margin-bottom: var(--spacing-md);
}

h1 { font-size: 3rem; }
h2 { font-size: 2.5rem; }
h3 { font-size: 2rem; }
h4 { font-size: 1.5rem; }
h5 { font-size: 1.25rem; }
h6 { font-size: 1rem; }

p {
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

/* ===== LAYOUT ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

/* ===== NAVIGATION ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: all var(--transition-normal);
}

[data-theme="dark"] .navbar,
.dark-mode .navbar {
    background: rgba(26, 26, 26, 0.95);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
    max-width: 1200px;
    margin: 0 auto;
}

.nav-logo .logo-text {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-menu {
    display: flex;
    gap: var(--spacing-lg);
    list-style: none;
}

.nav-link {
    color: var(--text-primary);
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-color);
    background-color: rgba(74, 144, 226, 0.1);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

.theme-toggle {
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.25rem;
    cursor: pointer;
    padding: var(--spacing-sm);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.theme-toggle:hover {
    background-color: var(--bg-secondary);
    color: var(--primary-color);
}

.menu-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-sm);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.menu-toggle span {
    width: 25px;
    height: 3px;
    background-color: var(--text-primary);
    margin: 3px 0;
    transition: var(--transition-fast);
    border-radius: 2px;
    transform-origin: center;
}

.menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
}

.menu-toggle:hover {
    background-color: var(--bg-secondary);
}

/* ===== MOBILE MENU ===== */
.mobile-menu {
    position: fixed;
    top: 70px;
    left: 0;
    right: 0;
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    padding: 0;
    transform: translateY(-100%);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
    z-index: 999;
    box-shadow: var(--shadow-medium);
}

.mobile-menu.active {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
}

.mobile-nav-link {
    display: block;
    padding: var(--spacing-md) var(--spacing-lg);
    color: var(--text-primary);
    border-bottom: 1px solid var(--border-color);
    transition: all var(--transition-fast);
    font-weight: 500;
    text-decoration: none;
}

.mobile-nav-link:hover {
    background-color: var(--bg-secondary);
    color: var(--primary-color);
    padding-left: calc(var(--spacing-lg) + var(--spacing-md));
}

.mobile-nav-link:last-child {
    border-bottom: none;
}

/* ===== MAIN CONTENT ===== */
main {
    margin-top: 70px;
    min-height: calc(100vh - 70px - 150px); /* Account for navbar and compact footer */
    padding-bottom: var(--spacing-lg);
    position: relative;
    z-index: 1;
}

/* ===== SECTIONS ===== */
.section {
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-lg) 0;
}

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

/* ===== PAGE HEADER ===== */
.page-header {
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    padding: var(--spacing-xl) 0;
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.page-header h1 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.page-header p {
    color: var(--text-secondary);
    font-size: 1.125rem;
}

/* ===== HERO SECTION ===== */
.hero-section {
    padding: var(--spacing-xl) 0;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
}

.hero-container {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: var(--spacing-xl);
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.hero-image {
    text-align: center;
}

.hero-image img {
    width: 300px;
    height: 300px;
    border-radius: 50%;
    object-fit: cover;
    border: 4px solid var(--primary-color);
    box-shadow: var(--shadow-medium);
    transition: transform var(--transition-normal);
}

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

.hero-content h1 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.hero-content h2 {
    color: var(--primary-color);
    font-size: 1.5rem;
    margin-bottom: var(--spacing-lg);
}

.research-areas {
    margin: var(--spacing-xl) 0;
}

.research-areas h3 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-md);
}

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

.tag {
    background-color: var(--primary-color);
    color: white;
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-lg);
    font-size: 0.875rem;
    font-weight: 500;
    transition: all var(--transition-fast);
}

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

.hero-actions {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-xl);
}

/* ===== BUTTONS ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: var(--radius-md);
    font-weight: 500;
    text-decoration: none;
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: 1rem;
}

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

.btn-primary:hover {
    background-color: var(--accent-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
}

.btn-secondary {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

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

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

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

.btn-small {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: 0.875rem;
}

/* ===== HIGHLIGHTS SECTION ===== */
.highlights-section {
    padding: var(--spacing-xl) 0;
    background-color: var(--bg-secondary);
}

.highlights-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.highlight-card {
    background: var(--bg-primary);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: var(--shadow-light);
    transition: all var(--transition-normal);
}

.highlight-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
}

.highlight-card i {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
}

.highlight-card h3 {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
}

.highlight-card p {
    color: var(--text-secondary);
    font-weight: 500;
}

/* ===== FEATURED SECTIONS ===== */
.section-footer {
    text-align: center;
    margin-top: var(--spacing-xl);
}

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

.project-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-light);
    transition: all var(--transition-normal);
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
}

.project-image {
    width: 100%;
    height: 200px;
    overflow: hidden;
}

.project-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-normal);
}

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

.project-content {
    padding: var(--spacing-xl);
}

.project-content h3 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin: var(--spacing-md) 0;
}

.project-actions {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
}

/* ===== PUBLICATIONS ===== */
.publications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.publication-card {
    background: var(--bg-primary);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-light);
    transition: all var(--transition-normal);
}

.publication-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-medium);
}

.publication-card h3 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.authors {
    color: var(--primary-color);
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
}

.venue {
    color: var(--text-secondary);
    font-style: italic;
    margin-bottom: var(--spacing-md);
}

.abstract {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

.publication-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.publication-actions {
    display: flex;
    gap: var(--spacing-sm);
}

/* ===== RESEARCH ===== */
.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.research-card {
    background: var(--bg-primary);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-light);
    transition: all var(--transition-normal);
}

.research-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-medium);
}

.research-card h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
}

.research-details {
    margin-top: var(--spacing-lg);
}

.research-details p {
    margin-bottom: var(--spacing-sm);
}

.status {
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-lg);
    font-size: 0.875rem;
    font-weight: 500;
}

.status.active {
    background-color: var(--secondary-color);
    color: white;
}

/* ===== BLOGS ===== */
.blogs-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-xl);
}

.blog-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-light);
    transition: all var(--transition-normal);
}

.blog-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
}

.blog-image {
    width: 100%;
    height: 200px;
    overflow: hidden;
}

.blog-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-normal);
}

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

.blog-content {
    padding: var(--spacing-xl);
}

.blog-content h3 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-md);
}

.blog-meta {
    display: flex;
    gap: var(--spacing-md);
    margin: var(--spacing-md) 0;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.blog-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin: var(--spacing-md) 0;
}

/* ===== EXPERIENCE ===== */
.timeline {
    position: relative;
    padding-left: var(--spacing-xl);
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--primary-color);
    border-radius: 1px;
}

.experience-card {
    position: relative;
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--shadow-light);
    transition: all var(--transition-normal);
}

.experience-card::before {
    content: '';
    position: absolute;
    left: -2.5rem;
    top: 1.5rem;
    width: 1rem;
    height: 1rem;
    background: var(--primary-color);
    border-radius: 50%;
    border: 3px solid var(--bg-primary);
    box-shadow: 0 0 0 3px var(--primary-color);
}

.experience-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
    border-color: var(--primary-color);
}

.experience-card h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
}

.company-info {
    margin-bottom: var(--spacing-md);
}

.company-info h4 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.location, .duration {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-right: var(--spacing-md);
}

.technologies {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-md);
}

.tech-tag {
    background: var(--bg-secondary);
    color: var(--text-primary);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    font-weight: 500;
    border: 1px solid var(--border-color);
    transition: all var(--transition-fast);
}

.tech-tag:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.achievements {
    margin-top: var(--spacing-md);
}

.achievements h5 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    font-size: 1rem;
}

.achievements ul {
    list-style: none;
    padding-left: 0;
}

.achievements li {
    position: relative;
    padding-left: var(--spacing-lg);
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
}

.achievements li::before {
    content: '▸';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

/* Hide experience cards when filtered out */
.experience-card[style*="display: none"] {
    display: none !important;
}

/* ===== CONTACT ===== */
.contact-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-3xl);
    margin-top: var(--spacing-xl);
}

.contact-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.contact-item i {
    font-size: 1.5rem;
    color: var(--primary-color);
    width: 40px;
}

.contact-item h3 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.contact-item p {
    color: var(--text-secondary);
    margin-bottom: 0;
}

.social-links {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-xl);
}

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

.social-link:hover {
    background-color: var(--primary-color);
    color: white;
    transform: translateY(-3px);
}

/* ===== CONTACT FORM ===== */
.contact-form {
    background: var(--bg-primary);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-light);
}

.contact-form h2 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-xl);
}

.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-family: var(--font-primary);
    transition: all var(--transition-fast);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.1);
}

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

/* ===== SEARCH AND FILTER ===== */
.search-filter-section {
    margin-bottom: var(--spacing-xl);
    padding: var(--spacing-lg);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
}

.search-box {
    position: relative;
    margin-bottom: var(--spacing-lg);
}

.search-box input {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-lg) var(--spacing-md) 3rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-lg);
    font-size: 1rem;
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: all var(--transition-fast);
}

.search-box input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(74, 144, 226, 0.1);
}

.search-box i {
    position: absolute;
    left: var(--spacing-md);
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.filter-section {
    margin-bottom: var(--spacing-lg);
}

.filter-section h4 {
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
    font-size: 1.1rem;
    font-weight: 600;
}

.filter-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.filter-btn {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: 0.9rem;
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    transform: translateY(-1px);
    box-shadow: var(--shadow-light);
}

.tag-filter-section {
    margin-bottom: var(--spacing-lg);
}

.tag-filter-section h4 {
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
    font-size: 1.1rem;
    font-weight: 600;
}

.tag-filter-buttons {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.tag-filter-btn {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: 0.9rem;
    position: relative;
    overflow: hidden;
}

.tag-filter-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left var(--transition-normal);
}

.tag-filter-btn:hover::before {
    left: 100%;
}

.tag-filter-btn:hover,
.tag-filter-btn.active {
    background: var(--secondary-color);
    color: white;
    border-color: var(--secondary-color);
    transform: translateY(-1px);
    box-shadow: var(--shadow-light);
}

.tag-filter-btn.active {
    background: var(--secondary-color);
    color: white;
    border-color: var(--secondary-color);
    box-shadow: var(--shadow-medium);
}

/* ===== FOOTER ===== */
.footer {
    background-color: var(--bg-secondary) !important;
    padding: var(--spacing-lg) 0 var(--spacing-md) !important;
    margin-top: var(--spacing-lg) !important;
    border-top: 1px solid var(--border-color);
    position: relative !important;
    bottom: auto !important;
    width: 100% !important;
    color: var(--text-primary) !important;
    text-align: left !important;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.footer-section h3,
.footer-section h4 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
    font-size: 1rem;
}

.footer-section p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    font-size: 0.85rem;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: var(--spacing-xs);
}

.footer-section ul li a {
    color: var(--text-secondary);
    transition: color var(--transition-fast);
    font-size: 0.85rem;
}

.footer-section ul li a:hover {
    color: var(--primary-color);
}

.footer-bottom {
    border-top: 1px solid var(--border-color);
    padding-top: var(--spacing-sm);
    text-align: center;
}

.footer-bottom p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
    font-size: 0.8rem;
}

/* ===== MODAL ===== */
.modal-container {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
}

.modal-container.active {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    max-width: 600px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
    position: relative;
    transform: scale(0.9);
    transition: transform var(--transition-normal);
}

.modal-container.active .modal-content {
    transform: scale(1);
}

.close {
    position: absolute;
    top: var(--spacing-md);
    right: var(--spacing-md);
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
    transition: color var(--transition-fast);
}

.close:hover {
    color: var(--text-primary);
}

/* ===== LOADING ===== */
.loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 400px;
    color: var(--text-secondary);
}

.spinner {
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: var(--spacing-md);
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* ===== RESPONSIVE DESIGN ===== */
@media (max-width: 1024px) {
    .hero-container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: var(--spacing-xl);
    }
    
    .hero-image img {
        width: 250px;
        height: 250px;
    }
    
    .contact-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .menu-toggle {
        display: flex;
    }
    
    .mobile-menu {
        display: block;
    }
    
    .hero-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .projects-grid,
    .publications-grid,
    .research-grid,
    .blogs-grid {
        grid-template-columns: 1fr;
    }
    
    .highlights-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .filter-buttons,
    .tag-filter-buttons {
        gap: var(--spacing-xs);
    }
    
    .filter-btn,
    .tag-filter-btn {
        padding: var(--spacing-xs) var(--spacing-sm);
        font-size: 0.85rem;
    }
    
    .search-box {
        margin-bottom: var(--spacing-md);
    }
    
    .filter-section,
    .tag-filter-section {
        margin-bottom: var(--spacing-md);
    }
    
    h1 { font-size: 2.5rem; }
    h2 { font-size: 2rem; }
    h3 { font-size: 1.75rem; }
}

@media (min-width: 769px) {
    .mobile-menu {
        display: none !important;
    }
    
    .menu-toggle {
        display: none !important;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-md);
    }
    
    .hero-image img {
        width: 200px;
        height: 200px;
    }
    
    .highlights-grid {
        grid-template-columns: 1fr;
    }
    
    .project-actions,
    .publication-actions {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    h1 { font-size: 2rem; }
    h2 { font-size: 1.75rem; }
    h3 { font-size: 1.5rem; }
}

/* ===== UTILITY CLASSES ===== */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mb-0 { margin-bottom: 0; }
.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.mb-4 { margin-bottom: var(--spacing-xl); }

.mt-0 { margin-top: 0; }
.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }
.mt-4 { margin-top: var(--spacing-xl); }

.hidden { display: none; }
.block { display: block; }
.flex { display: flex; }
.grid { display: grid; }

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

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

/* ===== SCROLLBAR STYLING ===== */
::-webkit-scrollbar {
    width: 8px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--text-secondary);
}

/* ===== SKILLS SECTION STYLES ===== */
.skills-section {
    margin-bottom: var(--spacing-3xl);
    padding: var(--spacing-xl) 0;
}

.skills-section h2 {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    color: var(--text-primary);
    font-size: 2.5rem;
    font-weight: 700;
}

.skill-category {
    margin-bottom: var(--spacing-2xl);
}

.skill-category h3 {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
    font-size: 1.75rem;
    font-weight: 600;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: var(--spacing-md);
}

.skill-category h3 i {
    color: var(--primary-color);
    font-size: 1.5rem;
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.skill-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
    position: relative;
    overflow: hidden;
}

.skill-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color));
    transform: scaleX(0);
    transition: transform var(--transition-normal);
}

.skill-card:hover::before {
    transform: scaleX(1);
}

.skill-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
    border-color: var(--primary-color);
}

.skill-card.expert::before {
    background: linear-gradient(90deg, #27ae60, #2ecc71);
}

.skill-card.advanced::before {
    background: linear-gradient(90deg, #3498db, #5dade2);
}

.skill-card.intermediate::before {
    background: linear-gradient(90deg, #f39c12, #f7dc6f);
}

.skill-card.beginner::before {
    background: linear-gradient(90deg, #e74c3c, #ec7063);
}

.skill-icon {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: center;
    height: 60px;
    width: 60px;
    border-radius: 50%;
    background: rgba(74, 144, 226, 0.1);
    margin: 0 auto var(--spacing-md);
}

.skill-content h4 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
    text-align: center;
}

.skill-level {
    display: flex;
    justify-content: center;
    margin-bottom: var(--spacing-md);
}

.level-badge {
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.level-badge.expert {
    background: rgba(39, 174, 96, 0.1);
    color: #27ae60;
    border: 1px solid rgba(39, 174, 96, 0.3);
}

.level-badge.advanced {
    background: rgba(52, 152, 219, 0.1);
    color: #3498db;
    border: 1px solid rgba(52, 152, 219, 0.3);
}

.level-badge.intermediate {
    background: rgba(243, 156, 18, 0.1);
    color: #f39c12;
    border: 1px solid rgba(243, 156, 18, 0.3);
}

.level-badge.beginner {
    background: rgba(231, 76, 60, 0.1);
    color: #e74c3c;
    border: 1px solid rgba(231, 76, 60, 0.3);
}

.skill-content p {
    text-align: center;
    color: var(--text-secondary);
    line-height: 1.6;
    margin: 0;
}

/* Research Skills Grid */
.research-skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.research-skill-card {
    background: var(--bg-primary);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.research-skill-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
    transform: scaleX(0);
    transition: transform var(--transition-normal);
}

.research-skill-card:hover::before {
    transform: scaleX(1);
}

.research-skill-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
    border-color: var(--primary-color);
}

.research-skill-card.expert::before {
    background: linear-gradient(90deg, #27ae60, #2ecc71);
}

.research-skill-card.advanced::before {
    background: linear-gradient(90deg, #3498db, #5dade2);
}

/* Soft Skills Grid */
.soft-skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.soft-skill-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.soft-skill-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--secondary-color), var(--accent-color));
    transform: scaleX(0);
    transition: transform var(--transition-normal);
}

.soft-skill-card:hover::before {
    transform: scaleX(1);
}

.soft-skill-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-medium);
    border-color: var(--secondary-color);
}

.soft-skill-card .skill-icon {
    font-size: 2rem;
    margin-bottom: var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: center;
    height: 50px;
    width: 50px;
    border-radius: 50%;
    background: rgba(80, 200, 120, 0.1);
    margin: 0 auto var(--spacing-md);
}

.soft-skill-card h4 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.soft-skill-card p {
    color: var(--text-secondary);
    line-height: 1.6;
    margin: 0;
    font-size: 0.9rem;
}

/* Certifications Grid */
.certifications-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.certification-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    position: relative;
    overflow: hidden;
}

.certification-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, #f39c12, #e67e22);
    transform: scaleX(0);
    transition: transform var(--transition-normal);
}

.certification-card:hover::before {
    transform: scaleX(1);
}

.certification-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-medium);
    border-color: #f39c12;
}

.cert-icon {
    font-size: 2.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 60px;
    width: 60px;
    border-radius: 50%;
    background: rgba(243, 156, 18, 0.1);
    flex-shrink: 0;
}

.cert-content h4 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.cert-issuer {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-xs);
}

.cert-date {
    color: var(--primary-color);
    font-size: 0.875rem;
    font-weight: 500;
}

/* Responsive Design for Skills */
@media (max-width: 768px) {
    .skills-grid,
    .research-skills-grid,
    .soft-skills-grid,
    .certifications-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }
    
    .skill-category h3 {
        font-size: 1.5rem;
    }
    
    .skill-card,
    .research-skill-card,
    .soft-skill-card,
    .certification-card {
        padding: var(--spacing-md);
    }
    
    .certification-card {
        flex-direction: column;
        text-align: center;
        gap: var(--spacing-md);
    }
    
    .skills-section h2 {
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .skill-icon,
    .cert-icon {
        font-size: 2rem;
        height: 50px;
        width: 50px;
    }
    
    .skill-content h4,
    .soft-skill-card h4,
    .cert-content h4 {
        font-size: 1rem;
    }
    
    .level-badge {
        font-size: 0.75rem;
        padding: var(--spacing-xs) var(--spacing-sm);
    }
}

/* ===== SKILLS PREVIEW SECTION ===== */
.skills-preview-section {
    background: var(--bg-secondary);
    padding: var(--spacing-3xl) 0;
    margin: var(--spacing-3xl) 0;
}

.skills-preview-section h2 {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    color: var(--text-primary);
    font-size: 2.5rem;
    font-weight: 700;
}

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

.skill-preview-category {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-light);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-color);
}

.skill-preview-category:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
    border-color: var(--primary-color);
}

.skill-preview-category h3 {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
    font-size: 1.25rem;
    font-weight: 600;
}

.skill-preview-category h3 i {
    color: var(--primary-color);
    font-size: 1.125rem;
}

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

.skill-preview-tag {
    padding: var(--spacing-xs) var(--spacing-sm);
    border: 2px solid;
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
    background: rgba(255, 255, 255, 0.1);
    transition: all var(--transition-fast);
    cursor: default;
}

.skill-preview-tag:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: scale(1.05);
}

/* Responsive Design for Skills Preview */
@media (max-width: 768px) {
    .skills-preview-grid {
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: var(--spacing-lg);
    }
    
    .skills-preview-section h2 {
        font-size: 2rem;
    }
    
    .skill-preview-category {
        padding: var(--spacing-md);
    }
}

@media (max-width: 480px) {
    .skills-preview-grid {
        grid-template-columns: 1fr;
    }
    
    .skill-preview-tags {
        justify-content: center;
    }
    
    .skills-preview-section h2 {
        font-size: 1.75rem;
    }
}

/* ===== CALL-TO-ACTION SECTION ===== */
.cta-section {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: var(--spacing-3xl) 0;
    margin-top: var(--spacing-3xl);
}

.cta-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.cta-content h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-lg);
    color: white;
}

.cta-content p {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-xl);
    color: rgba(255, 255, 255, 0.9);
    line-height: 1.6;
}

.cta-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

.cta-actions .btn {
    min-width: 160px;
    font-weight: 600;
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-lg);
    transition: all var(--transition-normal);
}

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

.cta-actions .btn-primary:hover {
    background: transparent;
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
}

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

.cta-actions .btn-secondary:hover {
    background: white;
    color: var(--secondary-color);
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
}

.cta-actions .btn-outline {
    background: transparent;
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.5);
}

.cta-actions .btn-outline:hover {
    background: white;
    color: var(--primary-color);
    border-color: white;
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
}

/* Responsive Design for CTA */
@media (max-width: 768px) {
    .cta-content h2 {
        font-size: 2rem;
    }
    
    .cta-content p {
        font-size: 1rem;
    }
    
    .cta-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .cta-actions .btn {
        width: 100%;
        max-width: 300px;
    }
}

@media (max-width: 480px) {
    .cta-content h2 {
        font-size: 1.75rem;
    }
    
    .cta-actions .btn {
        min-width: 140px;
        padding: var(--spacing-sm) var(--spacing-md);
    }
}

/* ===== SKILLS SUMMARY SECTION ===== */
.skills-summary-section {
    background: var(--bg-secondary);
    padding: var(--spacing-3xl) 0;
    margin-bottom: var(--spacing-3xl);
}

.skills-summary-section h2 {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    color: var(--text-primary);
    font-size: 2.5rem;
    font-weight: 700;
}

.skills-summary-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.summary-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    text-align: center;
    box-shadow: var(--shadow-light);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-color);
}

.summary-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
    border-color: var(--primary-color);
}

.summary-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: center;
    height: 60px;
    width: 60px;
    border-radius: 50%;
    background: rgba(74, 144, 226, 0.1);
    margin: 0 auto var(--spacing-md);
}

.summary-icon.expert {
    color: #27ae60;
    background: rgba(39, 174, 96, 0.1);
}

.summary-icon.advanced {
    color: #3498db;
    background: rgba(52, 152, 219, 0.1);
}

.summary-icon.research {
    color: #9b59b6;
    background: rgba(155, 89, 182, 0.1);
}

.summary-icon.cert {
    color: #f39c12;
    background: rgba(243, 156, 18, 0.1);
}

.summary-content h3 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
}

.summary-content p {
    color: var(--text-secondary);
    font-weight: 500;
    margin: 0;
}

.key-expertise {
    text-align: center;
}

.key-expertise h3 {
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
    font-size: 1.5rem;
    font-weight: 600;
}

.expertise-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    justify-content: center;
}

.expertise-tag {
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-lg);
    font-weight: 600;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.expertise-tag.primary {
    background: rgba(74, 144, 226, 0.1);
    color: var(--primary-color);
    border: 2px solid rgba(74, 144, 226, 0.3);
}

.expertise-tag.secondary {
    background: rgba(80, 200, 120, 0.1);
    color: var(--secondary-color);
    border: 2px solid rgba(80, 200, 120, 0.3);
}

.expertise-tag.accent {
    background: rgba(255, 107, 53, 0.1);
    color: var(--accent-color);
    border: 2px solid rgba(255, 107, 53, 0.3);
}

.expertise-tag.success {
    background: rgba(155, 89, 182, 0.1);
    color: #9b59b6;
    border: 2px solid rgba(155, 89, 182, 0.3);
}

.expertise-tag.warning {
    background: rgba(243, 156, 18, 0.1);
    color: #f39c12;
    border: 2px solid rgba(243, 156, 18, 0.3);
}

/* ===== OPEN SOURCE SECTION STYLES ===== */
.open-source-summary-section {
    background: var(--bg-secondary);
    padding: var(--spacing-3xl) 0;
    margin-bottom: var(--spacing-3xl);
}

.open-source-summary-section h2 {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    color: var(--text-primary);
    font-size: 2.5rem;
    font-weight: 700;
}

.open-source-summary-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
}

.open-source-summary-grid .summary-icon.stars {
    color: #f39c12;
    background: rgba(243, 156, 18, 0.1);
}

.open-source-summary-grid .summary-icon.forks {
    color: #27ae60;
    background: rgba(39, 174, 96, 0.1);
}

.open-source-summary-grid .summary-icon.contributions {
    color: #9b59b6;
    background: rgba(155, 89, 182, 0.1);
}

.open-source-summary-grid .summary-icon.packages {
    color: #e74c3c;
    background: rgba(231, 76, 60, 0.1);
}

.open-source-section {
    margin-bottom: var(--spacing-3xl);
    padding: var(--spacing-xl) 0;
}

.open-source-section h2 {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    color: var(--text-primary);
    font-size: 2.5rem;
    font-weight: 700;
}

/* Repository Cards */
.repositories-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.repository-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
}

.repository-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
    border-color: var(--primary-color);
}

.repo-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.repo-icon {
    font-size: 1.5rem;
    color: var(--primary-color);
}

.repo-stats {
    display: flex;
    gap: var(--spacing-md);
}

.repo-stat {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.repo-stat i {
    color: var(--primary-color);
}

.repo-content h4 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.repo-content p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

.repo-meta {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.repo-language {
    background: rgba(74, 144, 226, 0.1);
    color: var(--primary-color);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
}

.repo-status {
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
}

.repo-status.active {
    background: rgba(39, 174, 96, 0.1);
    color: #27ae60;
}

.repo-topics {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-md);
}

.repo-topic {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: 0.75rem;
}

/* Package Cards */
.packages-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.package-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
}

.package-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
    border-color: var(--secondary-color);
}

.package-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.package-icon {
    font-size: 1.5rem;
    color: var(--secondary-color);
}

.package-stat {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.package-stat i {
    color: var(--secondary-color);
}

.package-content h4 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--text-primary);
}

.package-content p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

.package-meta {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    flex-wrap: wrap;
}

.package-language,
.package-version {
    background: rgba(80, 200, 120, 0.1);
    color: var(--secondary-color);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
}

.package-status {
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
}

.package-status.maintained {
    background: rgba(39, 174, 96, 0.1);
    color: #27ae60;
}

/* Contribution Cards */
.contributions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.contribution-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
}

.contribution-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
}

.contribution-card.feature {
    border-left: 4px solid var(--primary-color);
}

.contribution-card.bug-fix {
    border-left: 4px solid var(--secondary-color);
}

.contribution-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.contribution-icon {
    font-size: 1.5rem;
    color: var(--primary-color);
}

.contribution-meta {
    display: flex;
    gap: var(--spacing-sm);
}

.contribution-type {
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
}

.contribution-type.feature {
    background: rgba(74, 144, 226, 0.1);
    color: var(--primary-color);
}

.contribution-type.bug-fix {
    background: rgba(80, 200, 120, 0.1);
    color: var(--secondary-color);
}

.contribution-status {
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: 0.75rem;
    font-weight: 500;
}

.contribution-status.merged {
    background: rgba(39, 174, 96, 0.1);
    color: #27ae60;
}

.contribution-content h4 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.contribution-org {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-sm);
}

.contribution-desc {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

.contribution-date {
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-bottom: var(--spacing-md);
}

/* Community Cards */
.community-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.community-card {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-light);
}

.community-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
    border-color: var(--accent-color);
}

.community-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.community-icon {
    font-size: 1.5rem;
    color: var(--accent-color);
}

.role-badge {
    background: rgba(255, 107, 53, 0.1);
    color: var(--accent-color);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
}

.community-content h4 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
}

.community-platform {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: var(--spacing-sm);
}

.community-desc {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

.community-impact {
    color: var(--text-secondary);
    font-size: 0.9rem;
    line-height: 1.6;
}

/* Responsive Design for Open Source */
@media (max-width: 768px) {
    .skills-summary-grid,
    .open-source-summary-grid,
    .repositories-grid,
    .packages-grid,
    .contributions-grid,
    .community-grid {
        grid-template-columns: 1fr;
        gap: var(--spacing-md);
    }
    
    .skills-summary-section h2,
    .open-source-summary-section h2,
    .open-source-section h2 {
        font-size: 2rem;
    }
    
    .expertise-tags {
        flex-direction: column;
        align-items: center;
    }
    
    .repo-meta,
    .package-meta {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
}

@media (max-width: 480px) {
    .summary-card,
    .repository-card,
    .package-card,
    .contribution-card,
    .community-card {
        padding: var(--spacing-md);
    }
    
    .skills-summary-section h2,
    .open-source-summary-section h2,
    .open-source-section h2 {
        font-size: 1.75rem;
    }
    
    .summary-content h3 {
        font-size: 1.5rem;
    }
}

/* ===== OPEN SOURCE PREVIEW SECTION ===== */
.open-source-preview-section {
    background: var(--bg-primary);
    padding: var(--spacing-3xl) 0;
    margin: var(--spacing-3xl) 0;
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.open-source-preview-section h2 {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    color: var(--text-primary);
    font-size: 2.5rem;
    font-weight: 700;
}

.open-source-preview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.open-source-preview-category {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-light);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-color);
}

.open-source-preview-category:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-medium);
    border-color: var(--primary-color);
}

.open-source-preview-category h3 {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
    font-size: 1.25rem;
    font-weight: 600;
}

.open-source-preview-category h3 i {
    color: var(--primary-color);
    font-size: 1.125rem;
}

.open-source-preview-stats {
    display: flex;
    gap: var(--spacing-lg);
    justify-content: space-around;
}

.preview-stat {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    display: block;
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

/* Responsive Design for Open Source Preview */
@media (max-width: 768px) {
    .open-source-preview-grid {
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: var(--spacing-lg);
    }
    
    .open-source-preview-section h2 {
        font-size: 2rem;
    }
    
    .open-source-preview-category {
        padding: var(--spacing-md);
    }
    
    .open-source-preview-stats {
        flex-direction: column;
        gap: var(--spacing-md);
    }
}

@media (max-width: 480px) {
    .open-source-preview-grid {
        grid-template-columns: 1fr;
    }
    
    .open-source-preview-section h2 {
        font-size: 1.75rem;
    }
    
    .stat-number {
        font-size: 1.5rem;
    }
}