/* ===== GLOBAL STYLES ===== */
:root {
    /* Color Palette - Green Theme */
    --primary-color: #059669;
    --primary-dark: #047857;
    --primary-light: #10b981;
    --secondary-color: #64748b;
    --accent-color: #34d399;
    --success-color: #10b981;
    --warning-color: #f59e0b;
    --error-color: #ef4444;

    /* Neutral Colors */
    --white: #ffffff;
    --gray-50: #f8fafc;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-400: #94a3b8;
    --gray-500: #64748b;
    --gray-600: #475569;
    --gray-700: #334155;
    --gray-800: #1e293b;
    --gray-900: #0f172a;

    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

    /* 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: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;

    /* Layout */
    --max-width: 1200px;
    --header-height: 80px;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-primary);
    line-height: 1.6;
    color: var(--gray-700);
    background-color: var(--white);
    overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    color: var(--gray-900);
    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: 1.125rem; }

p {
    margin-bottom: var(--spacing-md);
    color: var(--gray-600);
}

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

a:hover {
    color: var(--primary-dark);
}

/* Utility Classes */
.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-3xl);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: var(--spacing-md);
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
    border-radius: var(--radius-sm);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--gray-600);
    max-width: 600px;
    margin: 0 auto;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-md) var(--spacing-xl);
    font-weight: 500;
    font-size: 1rem;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    transition: all var(--transition-normal);
    text-decoration: none;
    position: relative;
    overflow: hidden;
}

.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-slow);
}

.btn:hover:before {
    left: 100%;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    color: var(--white);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    color: var(--white);
}

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

.btn-secondary:hover {
    background: var(--primary-color);
    color: var(--white);
    transform: translateY(-2px);
}

.btn-outline {
    background: transparent;
    color: var(--gray-700);
    border: 2px solid var(--gray-300);
}

.btn-outline:hover {
    background: var(--gray-900);
    color: var(--white);
    border-color: var(--gray-900);
}

.btn-full {
    width: 100%;
    justify-content: center;
}

/* 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(--gray-200);
    z-index: 1000;
    transition: all var(--transition-normal);
}

.navbar.scrolled {
    background: rgba(255, 255, 255, 0.98);
    box-shadow: var(--shadow-md);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--header-height);
    padding: 0 var(--spacing-xl);
}

.nav-logo a {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--gray-900);
    text-decoration: none;
}

.nav-menu {
    display: flex;
    gap: var(--spacing-xl);
}

.nav-link {
    color: var(--gray-700);
    font-weight: 500;
    text-decoration: none;
    padding: var(--spacing-sm) 0;
    position: relative;
    transition: color var(--transition-fast);
}

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

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

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

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

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

.nav-toggle .bar {
    width: 25px;
    height: 3px;
    background: var(--gray-700);
    border-radius: var(--radius-sm);
    transition: all var(--transition-normal);
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(rgba(0, 0, 0, 0.4), rgba(0, 0, 0, 0.6)), url('assets/images/hero-landscape.jpg') center/cover no-repeat;
    position: relative;
    overflow: hidden;
    color: var(--white);
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle, var(--primary-color)10, transparent 70%);
    opacity: 0.05;
    animation: float 20s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) rotate(0deg); }
    33% { transform: translate(30px, -30px) rotate(120deg); }
    66% { transform: translate(-20px, 20px) rotate(240deg); }
}

.hero-container {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.hero-image {
    margin-bottom: var(--spacing-xl);
}

.profile-img {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    object-fit: cover;
    border: 6px solid var(--white);
    box-shadow: var(--shadow-xl);
    transition: transform var(--transition-normal);
}

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

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: var(--spacing-sm);
    color: var(--white);
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--accent-color);
    margin-bottom: var(--spacing-lg);
    font-weight: 500;
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.5);
}

.hero-description {
    font-size: 1.125rem;
    color: var(--white);
    margin-bottom: var(--spacing-2xl);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.5);
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-lg);
    justify-content: center;
    margin-bottom: var(--spacing-2xl);
    flex-wrap: wrap;
}

.hero-social {
    display: flex;
    gap: var(--spacing-lg);
    justify-content: center;
}

.hero-social a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background: var(--white);
    color: var(--gray-600);
    border-radius: 50%;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    font-size: 1.25rem;
}

.hero-social a:hover {
    background: var(--primary-color);
    color: var(--white);
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.hero-scroll {
    position: absolute;
    bottom: var(--spacing-xl);
    left: 50%;
    transform: translateX(-50%);
}

.scroll-arrow {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    color: var(--gray-400);
    border: 2px solid var(--gray-300);
    border-radius: 50%;
    transition: all var(--transition-normal);
    animation: bounce 2s infinite;
}

.scroll-arrow:hover {
    color: var(--primary-color);
    border-color: var(--primary-color);
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
    40% { transform: translateY(-10px); }
    60% { transform: translateY(-5px); }
}

/* Sections */
section {
    padding: var(--spacing-3xl) 0;
}

section:nth-child(even) {
    background: var(--gray-50);
}

/* About Section */
.about-content {
    display: block;
}

.about-text {
    font-size: 1.125rem;
    line-height: 1.8;
    max-width: 900px;
    margin: 0 auto;
    text-align: center;
}

.about-stats {
    display: none;
}

.stat-item {
    display: none;
}

.stat-item:hover {
    display: none;
}

.stat-number {
    display: none;
}

.stat-label {
    display: none;
}

/* Timeline Styles */
.education-timeline,
.experience-timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.education-timeline::before,
.experience-timeline::before {
    content: '';
    position: absolute;
    left: 30px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--gray-200);
}

.timeline-item {
    position: relative;
    margin-bottom: var(--spacing-2xl);
    padding-left: 80px;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: 21px;
    top: 0;
    width: 20px;
    height: 20px;
    background: var(--primary-color);
    border-radius: 50%;
    border: 4px solid var(--white);
    box-shadow: var(--shadow-md);
}

.timeline-content {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
}

.timeline-content:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.timeline-year {
    display: inline-block;
    background: var(--primary-color);
    color: var(--white);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.timeline-content h3 {
    color: var(--gray-900);
    margin-bottom: var(--spacing-xs);
}

.timeline-content h4 {
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

.timeline-details,
.timeline-skills {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
}

.tag,
.skill-tag {
    background: var(--gray-100);
    color: var(--gray-700);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
}

.skill-tag {
    background: var(--accent-color);
    color: var(--white);
}

.timeline-content ul {
    margin: var(--spacing-md) 0;
    padding-left: var(--spacing-lg);
}

.timeline-content li {
    margin-bottom: var(--spacing-sm);
    color: var(--gray-600);
}

/* Research Section */
.research-categories {
    display: flex;
    justify-content: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-2xl);
    flex-wrap: wrap;
}

.filter-btn {
    padding: var(--spacing-md) var(--spacing-xl);
    background: var(--white);
    color: var(--gray-600);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-md);
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-normal);
}

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

.papers-grid {
    display: grid;
    gap: var(--spacing-xl);
}

.paper-card {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    border-left: 4px solid var(--primary-color);
    transition: all var(--transition-normal);
}

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

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

.paper-header h3 {
    margin-bottom: 0;
    color: var(--gray-900);
}

.paper-venue {
    background: var(--success-color);
    color: var(--white);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
    white-space: nowrap;
}

.paper-authors {
    color: var(--gray-600);
    margin-bottom: var(--spacing-md);
    font-style: italic;
}

.paper-abstract {
    color: var(--gray-700);
    line-height: 1.6;
    margin-bottom: var(--spacing-lg);
}

.paper-metrics {
    display: flex;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.metric {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--gray-500);
    font-size: 0.875rem;
}

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

.paper-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    color: var(--primary-color);
    font-weight: 500;
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

.paper-status {
    margin-bottom: var(--spacing-lg);
}

.status-badge {
    background: var(--warning-color);
    color: var(--white);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
}

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

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

.project-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-xl);
}

.project-image {
    position: relative;
    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(1.1);
}

.project-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.project-card:hover .project-overlay {
    opacity: 1;
}

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

.project-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background: var(--white);
    color: var(--gray-700);
    border-radius: 50%;
    transition: all var(--transition-normal);
    font-size: 1.25rem;
}

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

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

.project-content h3 {
    margin-bottom: var(--spacing-md);
    color: var(--gray-900);
}

.project-content p {
    color: var(--gray-600);
    margin-bottom: var(--spacing-lg);
}

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

.tech-tag {
    background: var(--gray-100);
    color: var(--gray-700);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
}

.project-stats {
    display: flex;
    gap: var(--spacing-lg);
    color: var(--gray-500);
    font-size: 0.875rem;
}

.project-stats span {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

/* Skills Section */
.skills-content {
    display: grid;
    gap: var(--spacing-2xl);
}

.skills-category {
    background: var(--white);
    padding: var(--spacing-2xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.skills-category h3 {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
    color: var(--gray-900);
}

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

.skills-list {
    display: grid;
    gap: var(--spacing-lg);
}

.skill-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-lg);
}

.skill-name {
    font-weight: 500;
    color: var(--gray-700);
    min-width: 120px;
}

.skill-bar {
    flex: 1;
    height: 8px;
    background: var(--gray-200);
    border-radius: var(--radius-md);
    overflow: hidden;
}

.skill-progress {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
    border-radius: var(--radius-md);
    transition: width 1s ease-out;
    width: 0;
}

.research-areas {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.research-tag {
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    color: var(--white);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-md);
    font-weight: 500;
    transition: transform var(--transition-normal);
}

.research-tag:hover {
    transform: translateY(-2px);
}

/* Blog Section */
.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
}

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

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

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

.blog-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.blog-category {
    position: absolute;
    top: var(--spacing-md);
    left: var(--spacing-md);
    background: var(--primary-color);
    color: var(--white);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 600;
}

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

.blog-meta {
    display: flex;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-md);
    color: var(--gray-500);
    font-size: 0.875rem;
}

.blog-meta span {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

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

.blog-content h3 a {
    color: var(--gray-900);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.blog-content h3 a:hover {
    color: var(--primary-color);
}

.blog-content p {
    margin-bottom: var(--spacing-lg);
}

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

.blog-tag {
    background: var(--gray-100);
    color: var(--gray-700);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
}

.blog-stats {
    display: flex;
    gap: var(--spacing-lg);
    color: var(--gray-500);
    font-size: 0.875rem;
}

.blog-stats span {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.blog-cta {
    text-align: center;
}

/* Contact Section */
.contact-content {
    display: flex;;
    gap: var(--spacing-3xl);
    align-items: start;
}

.contact-info h3 {
    margin-bottom: var(--spacing-lg);
    color: var(--gray-900);
}

.contact-info p {
    margin-bottom: var(--spacing-xl);
    font-size: 1.125rem;
    max-width: 600px;  /* optional: prevent it from stretching too wide */
}

.contact-details {
    margin-bottom: var(--spacing-2xl);
}

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

.contact-item i {
    color: var(--primary-color);
    font-size: 1.25rem;
    margin-top: 4px;
    width: 24px;
}

.contact-item strong {
    color: var(--gray-900);
    display: block;
    margin-bottom: var(--spacing-xs);
}

.contact-item p {
    margin-bottom: 0;
    color: var(--gray-600);
}

.contact-social {
    display: flex;
    gap: var(--spacing-md);
}

.contact-social a {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: var(--white);
    border-radius: 50%;
    transition: all var(--transition-normal);
    font-size: 1.25rem;
}

.contact-social a:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
}

/* Contact Form */
.contact-form {
    background: var(--white);
    padding: var(--spacing-2xl);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
}

.form-group {
    position: relative;
    margin-bottom: var(--spacing-xl);
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: var(--spacing-lg) var(--spacing-md);
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-family: inherit;
    background: var(--white);
    transition: all var(--transition-normal);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-group label {
    position: absolute;
    left: var(--spacing-md);
    top: 50%;
    transform: translateY(-50%);
    color: var(--gray-500);
    font-size: 1rem;
    transition: all var(--transition-normal);
    pointer-events: none;
    background: var(--white);
    padding: 0 var(--spacing-xs);
}

.form-group textarea + label {
    top: var(--spacing-lg);
    transform: none;
}

.form-group input:focus + label,
.form-group input:not(:placeholder-shown) + label,
.form-group textarea:focus + label,
.form-group textarea:not(:placeholder-shown) + label {
    top: 0;
    transform: translateY(-50%);
    color: var(--primary-color);
    font-size: 0.875rem;
}

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

/* Footer */
.footer {
    background: var(--gray-900);
    color: var(--gray-300);
    padding: var(--spacing-3xl) 0 var(--spacing-xl);
}

.footer-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: var(--spacing-3xl);
}

.footer-info h3 {
    color: var(--white);
    margin-bottom: var(--spacing-md);
}

.footer-info p {
    color: var(--gray-400);
    margin-bottom: var(--spacing-sm);
}

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

.footer-section h4 {
    color: var(--white);
    margin-bottom: var(--spacing-lg);
    font-size: 1.125rem;
}

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

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

.footer-section a {
    color: var(--gray-400);
    text-decoration: none;
    transition: color var(--transition-fast);
}

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

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: var(--spacing-xl);
    right: var(--spacing-xl);
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: var(--white);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    font-size: 1.25rem;
    box-shadow: var(--shadow-lg);
    transition: all var(--transition-normal);
    opacity: 0;
    visibility: hidden;
    z-index: 1000;
}

.back-to-top.visible {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    background: var(--primary-dark);
    transform: translateY(-3px);
}

/* Responsive Design */
@media (max-width: 768px) {
    :root {
        --spacing-3xl: 2rem;
        --spacing-2xl: 1.5rem;
    }

    .container {
        padding: 0 var(--spacing-md);
    }

    /* Navigation */
    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: -100%;
        width: 100%;
        height: calc(100vh - var(--header-height));
        background: var(--white);
        flex-direction: column;
        justify-content: flex-start;
        align-items: center;
        padding-top: var(--spacing-2xl);
        transition: left var(--transition-normal);
        z-index: 999;
        box-shadow: var(--shadow-lg);
    }

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

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.active .bar:nth-child(1) {
        transform: rotate(45deg) translate(7px, 7px);
    }

    .nav-toggle.active .bar:nth-child(2) {
        opacity: 0;
    }

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

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

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

    .btn {
        width: 100%;
        max-width: 300px;
    }

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

    /* About */
    .about-content {
        display: block;
    }

    .about-text {
        text-align: left;
    }

    /* Timeline */
    .education-timeline::before,
    .experience-timeline::before {
        left: 15px;
    }

    .timeline-item {
        padding-left: 50px;
    }

    .timeline-item::before {
        left: 6px;
        width: 18px;
        height: 18px;
    }

    .timeline-content {
        padding: var(--spacing-lg);
    }

    /* Projects */
    .projects-grid {
        grid-template-columns: 1fr;
    }

    /* Skills */
    .skill-item {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-sm);
    }

    .skill-name {
        min-width: auto;
    }

    .skill-bar {
        width: 100%;
    }

    /* Contact */
    .contact-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
    }

    .contact-form {
        padding: var(--spacing-xl);
    }

    /* Footer */
    .footer-content {
        grid-template-columns: 1fr;
        gap: var(--spacing-xl);
        text-align: center;
    }

    .footer-links {
        grid-template-columns: 1fr;
    }
}

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

    .hero-subtitle {
        font-size: 1.25rem;
    }

    .profile-img {
        width: 150px;
        height: 150px;
    }



    .research-categories {
        gap: var(--spacing-sm);
    }

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

    .hero-social {
        gap: var(--spacing-md);
    }

    .hero-social a {
        width: 45px;
        height: 45px;
        font-size: 1.125rem;
    }
}

/* Animation Classes */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Loading Animation */
.loading {
    position: relative;
    overflow: hidden;
}

.loading::after {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.6), transparent);
    animation: loading 1.5s infinite;
}

@keyframes loading {
    0% { left: -100%; }
    100% { left: 100%; }
}

/* Print Styles */
@media print {
    .navbar,
    .hero-scroll,
    .back-to-top,
    .contact-form {
        display: none;
    }

    body {
        font-size: 12pt;
        line-height: 1.4;
    }

    .hero {
        min-height: auto;
        padding: 2rem 0;
    }

    section {
        page-break-inside: avoid;
        padding: 1rem 0;
    }

    .container {
        max-width: none;
        padding: 0;
    }
}