/* =============================================================================
   CSS Variables for Theme Management
   ============================================================================= */
:root {
    /* Light Theme Colors */
    --primary-color: #2563eb;
    --primary-dark: #1e40af;
    --primary-light: #3b82f6;
    --secondary-color: #10b981;
    --accent-color: #f59e0b;
    
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;
    --bg-card: #ffffff;
    
    --text-primary: #111827;
    --text-secondary: #4b5563;
    --text-tertiary: #6b7280;
    --text-inverse: #ffffff;
    
    --border-color: #e5e7eb;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.15);
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Container */
    --container-max-width: 1200px;
}

/* Dark Theme */
[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --bg-card: #1e293b;
    
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-tertiary: #94a3b8;
    
    --border-color: #334155;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.4);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.5);
}

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

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

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

/* =============================================================================
   Typography
   ============================================================================= */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    color: var(--text-primary);
}

h1 { font-size: 3rem; }
h2 { font-size: 2.5rem; }
h3 { font-size: 1.75rem; }
h4 { font-size: 1.5rem; }
h5 { font-size: 1.25rem; }
h6 { font-size: 1rem; }

p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

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

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

.lead {
    font-size: 1.25rem;
    font-weight: 500;
    color: var(--text-primary);
}

.highlight {
    color: var(--primary-color);
    background: linear-gradient(120deg, var(--primary-light) 0%, var(--secondary-color) 100%);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

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

.section {
    padding: var(--spacing-2xl) 0;
}

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

.section-title {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-sm);
    position: relative;
    display: inline-block;
}

.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(--secondary-color));
    border-radius: var(--radius-full);
}

.section-subtitle {
    font-size: 1.1rem;
    color: var(--text-tertiary);
    margin-top: var(--spacing-md);
}

/* =============================================================================
   Navigation
   ============================================================================= */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: var(--bg-card);
    box-shadow: var(--shadow-md);
    z-index: 1000;
    transition: all var(--transition-normal);
}

.navbar.scrolled {
    padding: 0.5rem 0;
    box-shadow: var(--shadow-lg);
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    padding-bottom: 1rem;
}

.nav-brand a {
    font-size: 1.75rem;
    font-weight: 800;
    color: var(--primary-color);
    transition: transform var(--transition-fast);
    display: inline-block;
}

.nav-brand a:hover {
    transform: scale(1.05);
}

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

.nav-link {
    color: var(--text-secondary);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
    transition: color var(--transition-fast);
}

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

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

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

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

.theme-toggle,
.mobile-menu-toggle {
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.25rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover,
.mobile-menu-toggle:hover {
    background-color: var(--bg-tertiary);
    transform: scale(1.1);
}

.mobile-menu-toggle {
    display: none;
}

/* =============================================================================
   Hero Section
   ============================================================================= */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: 80px;
    position: relative;
    overflow: hidden;
}

.hero-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: center;
    position: relative;
    z-index: 2;
}

.hero-title {
    font-size: 3.5rem;
    margin-bottom: var(--spacing-sm);
    animation: fadeInUp 0.8s ease;
}

.hero-subtitle {
    font-size: 1.75rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
    animation: fadeInUp 0.8s ease 0.2s backwards;
}

.hero-description {
    font-size: 1.1rem;
    color: var(--text-tertiary);
    margin-bottom: var(--spacing-lg);
    line-height: 1.8;
    animation: fadeInUp 0.8s ease 0.4s backwards;
}

.hero-cta {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
    animation: fadeInUp 0.8s ease 0.6s backwards;
    flex-wrap: nowrap;
    align-items: center;
    justify-content: center;
}

.hero-social {
    display: flex;
    gap: var(--spacing-md);
    animation: fadeInUp 0.8s ease 0.8s backwards;
}

.social-link {
    width: 45px;
    height: 45px;
    border-radius: var(--radius-full);
    background-color: var(--bg-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-primary);
    font-size: 1.2rem;
    transition: all var(--transition-fast);
}

.social-link:hover {
    background-color: var(--primary-color);
    color: var(--text-inverse);
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.hero-image {
    animation: fadeInRight 1s ease;
}

.profile-card {
    background-color: var(--bg-card);
    border-radius: var(--radius-2xl);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-xl);
    border: 1px solid var(--border-color);
    transition: transform var(--transition-normal);
}

.profile-card:hover {
    transform: translateY(-10px);
}

.profile-avatar {
    width: 200px;
    height: 200px;
    margin: 0 auto var(--spacing-lg);
    border-radius: var(--radius-full);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 5rem;
    color: white;
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

.profile-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
    border-radius: var(--radius-full);
}

.profile-info {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.info-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.info-item i {
    color: var(--primary-color);
    font-size: 1.1rem;
    width: 24px;
}

/* Hero Background Shapes */
.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
    overflow: hidden;
}

.bg-shape {
    position: absolute;
    border-radius: 50%;
    opacity: 0.05;
    animation: float 20s ease-in-out infinite;
}

.shape-1 {
    width: 500px;
    height: 500px;
    background: var(--primary-color);
    top: -250px;
    right: -100px;
}

.shape-2 {
    width: 400px;
    height: 400px;
    background: var(--secondary-color);
    bottom: -200px;
    left: -100px;
    animation-delay: -5s;
}

.shape-3 {
    width: 300px;
    height: 300px;
    background: var(--accent-color);
    top: 50%;
    left: 50%;
    animation-delay: -10s;
}

/* =============================================================================
   Buttons
   ============================================================================= */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-lg);
    border: none;
    cursor: pointer;
    transition: all var(--transition-fast);
    text-decoration: none;
    white-space: nowrap;
}

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

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

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

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

.btn-tertiary {
    background-color: var(--accent-color);
    color: var(--text-inverse);
    border: 2px solid var(--accent-color);
}

.btn-tertiary:hover {
    background-color: transparent;
    color: var(--accent-color);
    border-color: var(--accent-color);
    transform: translateY(-2px);
}

/* =============================================================================
   About Section
   ============================================================================= */
.about {
    background-color: var(--bg-secondary);
}

.about-text {
    max-width: 900px;
    margin: 0 auto;
}

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

.highlight-item {
    background-color: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-color);
    text-align: center;
    transition: all var(--transition-normal);
}

.highlight-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

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

.highlight-item h3 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-sm);
}

.highlight-item p {
    color: var(--text-tertiary);
    font-size: 0.95rem;
}

/* =============================================================================
   Experience Timeline
   ============================================================================= */
.timeline {
    position: relative;
    max-width: 900px;
    margin: 0 auto;
    padding-left: 50px;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 0;
    bottom: 0;
    width: 3px;
    background: linear-gradient(180deg, var(--primary-color), var(--secondary-color));
}

.timeline-item {
    position: relative;
    margin-bottom: var(--spacing-xl);
    animation: fadeInLeft 0.6s ease;
}

.timeline-marker {
    position: absolute;
    left: -38px;
    top: 0;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    background-color: var(--primary-color);
    border: 4px solid var(--bg-primary);
    box-shadow: 0 0 0 4px var(--primary-light);
}

.timeline-content {
    background-color: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
}

.timeline-content:hover {
    transform: translateX(10px);
    box-shadow: var(--shadow-lg);
}

.timeline-header {
    margin-bottom: var(--spacing-md);
}

.timeline-header h3 {
    font-size: 1.5rem;
    margin-bottom: 0.25rem;
}

.company {
    color: var(--primary-color);
    font-weight: 600;
    font-size: 1.1rem;
    display: block;
    margin-bottom: 0.25rem;
}

.period {
    color: var(--text-tertiary);
    font-size: 0.9rem;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

.period::before {
    content: '📅';
}

.achievement-list {
    list-style: none;
    margin-bottom: var(--spacing-md);
}

.achievement-list li {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
    line-height: 1.7;
}

.achievement-list i {
    color: var(--secondary-color);
    margin-top: 4px;
    flex-shrink: 0;
}

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

.tag {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    padding: 0.35rem 0.75rem;
    border-radius: var(--radius-full);
    font-size: 0.85rem;
    font-weight: 500;
    transition: all var(--transition-fast);
}

.tag:hover {
    background-color: var(--primary-color);
    color: var(--text-inverse);
    transform: scale(1.05);
}

/* =============================================================================
   Skills Section
   ============================================================================= */
.skills {
    background-color: var(--bg-secondary);
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-lg);
}

.skill-category {
    background-color: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
    animation: fadeIn 0.6s ease;
}

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

.category-icon {
    width: 60px;
    height: 60px;
    border-radius: var(--radius-lg);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.75rem;
    margin-bottom: var(--spacing-md);
}

.skill-category h3 {
    font-size: 1.35rem;
    margin-bottom: var(--spacing-md);
}

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

.skill-tag {
    background-color: var(--bg-tertiary);
    color: var(--text-secondary);
    padding: 0.5rem 1rem;
    border-radius: var(--radius-full);
    font-size: 0.9rem;
    font-weight: 500;
    transition: all var(--transition-fast);
    border: 1px solid transparent;
}

.skill-tag:hover {
    background-color: var(--primary-light);
    color: var(--text-inverse);
    border-color: var(--primary-color);
    transform: translateY(-2px);
}

/* =============================================================================
   Education Section
   ============================================================================= */
.education-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-lg);
}

.education-item {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    transition: all var(--transition-normal);
}

.education-item:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-lg);
    transform: translateY(-5px);
}

.education-header h3 {
    font-size: 1.25rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.education-school {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.education-gpa {
    font-size: 0.95rem;
    color: var(--primary-color);
    font-weight: 600;
}

/* =============================================================================
   Projects Section
   ============================================================================= */
.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-lg);
}

.project-card {
    background-color: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
    animation: fadeIn 0.6s ease;
}

.project-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.project-icon {
    width: 70px;
    height: 70px;
    border-radius: var(--radius-lg);
    background: linear-gradient(135deg, var(--primary-light), var(--secondary-color));
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 2rem;
    margin-bottom: var(--spacing-md);
}

.project-card h3 {
    font-size: 1.35rem;
    margin-bottom: var(--spacing-sm);
}

.project-card p {
    color: var(--text-tertiary);
    margin-bottom: var(--spacing-md);
    line-height: 1.7;
}

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

/* =============================================================================
   Contact Section
   ============================================================================= */
.contact {
    background-color: var(--bg-secondary);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: var(--spacing-xl);
    max-width: 1000px;
    margin: 0 auto;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.contact-item {
    display: flex;
    gap: var(--spacing-md);
    background-color: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
}

.contact-item:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}

.contact-icon {
    width: 50px;
    height: 50px;
    border-radius: var(--radius-lg);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.25rem;
    flex-shrink: 0;
}

.contact-details h3 {
    font-size: 1.1rem;
    margin-bottom: 0.25rem;
}

.contact-details p,
.contact-details a {
    color: var(--text-tertiary);
    font-size: 0.95rem;
}

.contact-form-wrapper {
    background-color: var(--bg-card);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-md);
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

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

.form-group label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.95rem;
}

.form-group input,
.form-group textarea {
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-family: inherit;
    font-size: 1rem;
    background-color: var(--bg-primary);
    color: var(--text-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(37, 99, 235, 0.1);
}

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

/* =============================================================================
   Footer
   ============================================================================= */
.footer {
    background-color: var(--bg-card);
    padding: var(--spacing-xl) 0;
    border-top: 1px solid var(--border-color);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.footer-content p {
    color: var(--text-tertiary);
    margin: 0;
}

.footer-social {
    display: flex;
    gap: var(--spacing-sm);
}

.footer-social a {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-full);
    background-color: var(--bg-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-primary);
    transition: all var(--transition-fast);
}

.footer-social a:hover {
    background-color: var(--primary-color);
    color: var(--text-inverse);
    transform: translateY(-3px);
}

/* =============================================================================
   Back to Top Button
   ============================================================================= */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    border-radius: var(--radius-full);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-lg);
    z-index: 999;
}

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

.back-to-top:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

/* =============================================================================
   Animations
   ============================================================================= */
@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

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

@keyframes fadeInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes fadeInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes float {
    0%, 100% {
        transform: translate(0, 0) rotate(0deg);
    }
    25% {
        transform: translate(50px, -50px) rotate(90deg);
    }
    50% {
        transform: translate(0, -100px) rotate(180deg);
    }
    75% {
        transform: translate(-50px, -50px) rotate(270deg);
    }
}

/* =============================================================================
   Responsive Design
   ============================================================================= */
@media (max-width: 968px) {
    .hero-content {
        grid-template-columns: 1fr;
    }
    
    .hero-image {
        order: -1;
    }
    
    .profile-card {
        max-width: 400px;
        margin: 0 auto;
    }
    
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .skills-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    html {
        font-size: 14px;
    }
    
    h1 { font-size: 2.5rem; }
    h2 { font-size: 2rem; }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.5rem;
    }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background-color: var(--bg-card);
        flex-direction: column;
        padding: var(--spacing-xl);
        gap: var(--spacing-md);
        transition: left var(--transition-normal);
        box-shadow: var(--shadow-xl);
        align-items: flex-start;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .hero-cta {
        flex-direction: column;
    }
    
    .timeline {
        padding-left: 30px;
    }
    
    .timeline::before {
        left: 10px;
    }
    
    .timeline-marker {
        left: -28px;
        width: 16px;
        height: 16px;
    }
    
    .section {
        padding: var(--spacing-xl) 0;
    }
    
    .projects-grid,
    .about-highlights {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 var(--spacing-md);
    }
    
    .hero-cta .btn {
        width: 100%;
        justify-content: center;
    }
    
    .profile-avatar {
        width: 150px;
        height: 150px;
        font-size: 4rem;
    }
    
    .back-to-top {
        bottom: 20px;
        right: 20px;
        width: 45px;
        height: 45px;
    }
}

/* =============================================================================
   Utility Classes
   ============================================================================= */
.text-center {
    text-align: center;
}

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

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

.hidden {
    display: none;
}

.visible {
    display: block;
}