/* ============================================
   Neil Sharma - Academic Portfolio
   Modern, Clean Design
   ============================================ */

/* ============================================
   CSS Variables
   ============================================ */
:root {
    /* Colors */
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #3b82f6;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --bg-white: #ffffff;
    --bg-light: #f9fafb;
    --bg-dark: #111827;
    --border-color: #e5e7eb;
    --shadow: 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);
    
    /* Typography */
    --font-primary: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-secondary: 'Roboto', sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
    font-family: var(--font-secondary);
    color: var(--text-dark);
    line-height: 1.6;
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-primary);
    font-weight: 600;
    line-height: 1.3;
    margin-bottom: 1rem;
}

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

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

img {
    max-width: 100%;
    height: auto;
    display: block;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

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

/* ============================================
   Navigation
   ============================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow);
    z-index: 1000;
    transition: var(--transition);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

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

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

.nav-link {
    color: var(--text-dark);
    font-weight: 500;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-md);
    transition: var(--transition);
}

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

.nav-toggle {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-dark);
}

/* ============================================
   Hero Section
   ============================================ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: 80px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    background: linear-gradient(135deg, var(--bg-light) 0%, #e0e7ff 100%);
    position: relative;
}

.hero-container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.hero-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: var(--spacing-lg);
    align-items: center;
}

.hero-greeting {
    font-size: 1.5rem;
    color: var(--primary-color);
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.highlight {
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.8rem;
    color: var(--text-light);
    font-weight: 400;
    margin-bottom: var(--spacing-md);
}

.hero-description {
    font-size: 1.1rem;
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: var(--spacing-md);
    max-width: 600px;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
    flex-wrap: wrap;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 1.75rem;
    border-radius: var(--radius-full);
    font-weight: 600;
    font-size: 1rem;
    transition: var(--transition);
    cursor: pointer;
    border: none;
}

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

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

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

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

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

.social-links a {
    width: 48px;
    height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: white;
    border-radius: var(--radius-full);
    font-size: 1.25rem;
    color: var(--primary-color);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

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

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
}

.profile-img {
    width: 100%;
    max-width: 400px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    border: 8px solid white;
    transition: var(--transition);
}

.profile-img:hover {
    transform: scale(1.02);
}

.scroll-down {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
}

.scroll-down a {
    font-size: 2rem;
    color: var(--primary-color);
    animation: bounce 2s infinite;
}

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

/* ============================================
   Section Titles
   ============================================ */
.section-title {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: var(--spacing-lg);
    position: relative;
    padding-bottom: 1rem;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
    border-radius: var(--radius-full);
}

.subsection-title {
    font-size: 1.8rem;
    margin: var(--spacing-lg) 0 var(--spacing-md) 0;
    color: var(--text-dark);
}

/* ============================================
   About Section
   ============================================ */
.about-section {
    background: white;
}

.about-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: var(--spacing-lg);
}

.about-text {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-light);
}

.about-text p {
    margin-bottom: 1.5rem;
}

.research-interests {
    background: var(--bg-light);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
}

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

.interests-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-sm);
}

.interest-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem;
    background: white;
    border-radius: var(--radius-md);
    transition: var(--transition);
}

.interest-item:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow);
}

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

/* ============================================
   Research Section
   ============================================ */
.research-section {
    background: var(--bg-light);
}

.research-highlight {
    background: white;
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    margin-bottom: var(--spacing-lg);
    border-left: 4px solid var(--primary-color);
}

.research-tag {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.research-highlight h3 {
    font-size: 1.8rem;
    color: var(--text-dark);
    margin-bottom: 1rem;
}

.research-highlight p {
    color: var(--text-light);
    margin-bottom: 1rem;
    line-height: 1.8;
}

.research-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.badge {
    padding: 0.5rem 1rem;
    background: var(--bg-light);
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    color: var(--primary-color);
    font-weight: 500;
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
}

.project-card {
    background: white;
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

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

.project-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.project-card h4 {
    font-size: 1.3rem;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

.project-card p {
    color: var(--text-light);
    margin-bottom: 1rem;
    line-height: 1.6;
}

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

.tag {
    padding: 0.25rem 0.75rem;
    background: var(--bg-light);
    border-radius: var(--radius-full);
    font-size: 0.813rem;
    color: var(--primary-color);
}

/* ============================================
   Publications Section
   ============================================ */
.publications-section {
    background: white;
}

.publications-list {
    max-width: 900px;
    margin: 0 auto;
}

.publication-item {
    display: grid;
    grid-template-columns: 80px 1fr;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    background: var(--bg-light);
    border-radius: var(--radius-lg);
    transition: var(--transition);
}

.publication-item:hover {
    box-shadow: var(--shadow-lg);
    transform: translateX(5px);
}

.publication-item.under-review {
    border-left: 4px solid #f59e0b;
}

.pub-year {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.pub-title {
    font-size: 1.3rem;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

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

.pub-venue {
    color: var(--text-light);
    font-style: italic;
    margin-bottom: 0.75rem;
}

.status-badge {
    background: #fef3c7;
    color: #92400e;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 600;
    margin-left: 0.5rem;
}

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

.pub-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: white;
    border-radius: var(--radius-md);
    color: var(--primary-color);
    font-size: 0.875rem;
    font-weight: 500;
    transition: var(--transition);
}

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

/* ============================================
   Experience Section
   ============================================ */
.experience-section {
    background: var(--bg-light);
}

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

.timeline::before {
    content: '';
    position: absolute;
    left: 40px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--border-color);
}

.timeline-item {
    position: relative;
    padding-left: 100px;
    margin-bottom: var(--spacing-lg);
}

.timeline-marker {
    position: absolute;
    left: 32px;
    top: 0;
    width: 18px;
    height: 18px;
    background: var(--primary-color);
    border: 4px solid white;
    border-radius: var(--radius-full);
    box-shadow: var(--shadow);
}

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

.timeline-date {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-full);
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
}

.timeline-content h3 {
    font-size: 1.5rem;
    color: var(--text-dark);
    margin-bottom: 0.25rem;
}

.timeline-content h4 {
    font-size: 1.1rem;
    color: var(--primary-color);
    font-weight: 500;
    margin-bottom: 0.75rem;
}

.timeline-content p {
    color: var(--text-light);
    line-height: 1.6;
    margin-bottom: 1rem;
}

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

/* ============================================
   Teaching Section
   ============================================ */
.teaching-section {
    background: white;
}

.teaching-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: var(--spacing-lg);
}

.teaching-main h3 {
    font-size: 1.8rem;
    color: var(--text-dark);
    margin-bottom: 1rem;
}

.teaching-meta {
    color: var(--text-light);
    margin-bottom: 1.5rem;
    font-size: 0.95rem;
}

.teaching-meta i {
    color: var(--primary-color);
    margin-right: 0.25rem;
}

.topics-taught {
    margin-top: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--bg-light);
    border-radius: var(--radius-lg);
}

.topics-taught h4 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.topics-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-sm);
}

.topic-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem;
    background: white;
    border-radius: var(--radius-md);
}

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

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

.info-card {
    background: var(--bg-light);
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
}

.info-card h4 {
    color: var(--primary-color);
    margin-bottom: 0.75rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

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

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

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

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

.contact-item {
    display: flex;
    gap: 1.5rem;
    background: white;
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
}

.contact-icon {
    width: 60px;
    height: 60px;
    background: var(--primary-color);
    color: white;
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    flex-shrink: 0;
}

.contact-details h4 {
    font-size: 1.1rem;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.contact-details p,
.contact-details a {
    color: var(--text-light);
    line-height: 1.6;
}

.social-links-contact {
    display: flex;
    gap: 0.75rem;
    margin-top: 0.5rem;
}

.social-links-contact a {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-light);
    border-radius: var(--radius-full);
    color: var(--primary-color);
    transition: var(--transition);
}

.social-links-contact a:hover {
    background: var(--primary-color);
    color: white;
}

.contact-cta {
    background: white;
    padding: var(--spacing-md);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
}

.contact-cta h3 {
    font-size: 1.8rem;
    color: var(--text-dark);
    margin-bottom: 1rem;
}

.contact-cta p {
    color: var(--text-light);
    line-height: 1.8;
    margin-bottom: var(--spacing-md);
}

/* ============================================
   Footer
   ============================================ */
.footer {
    background: var(--bg-dark);
    color: white;
    padding: var(--spacing-md) 0;
    text-align: center;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.footer-content p {
    margin: 0.5rem 0;
    color: rgba(255, 255, 255, 0.8);
}

/* ============================================
   Responsive Design
   ============================================ */
@media (max-width: 968px) {
    .hero-content,
    .about-content,
    .teaching-content,
    .contact-content {
        grid-template-columns: 1fr;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.5rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .timeline::before {
        left: 20px;
    }
    
    .timeline-item {
        padding-left: 60px;
    }
    
    .timeline-marker {
        left: 12px;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--shadow-lg);
        padding: 2rem 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .nav-toggle {
        display: block;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1.25rem;
    }
    
    .hero-description {
        font-size: 1rem;
    }
    
    .interests-grid,
    .topics-grid {
        grid-template-columns: 1fr;
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
    }
    
    .publication-item {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    .social-links {
        justify-content: center;
    }
}

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

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

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

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

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