/* ===========================
   CSS Reset & Base Styles
   =========================== */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Color Palette */
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --text-color: #333;
    --text-light: #666;
    --bg-color: #ffffff;
    --bg-alt: #f8f9fa;
    --border-color: #e0e0e0;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.16);
    
    /* Typography */
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-heading: 'Playfair Display', serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

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

body {
    font-family: var(--font-main);
    color: var(--text-color);
    line-height: 1.7;
    background-color: var(--bg-color);
    overflow-x: hidden;
}

/* ===========================
   Typography
   =========================== */

h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.3;
    color: var(--primary-color);
}

h1 {
    font-size: 3rem;
}

h2 {
    font-size: 2.5rem;
}

h3 {
    font-size: 1.75rem;
}

h4 {
    font-size: 1.25rem;
}

p {
    margin-bottom: 1rem;
}

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

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

/* ===========================
   Layout
   =========================== */

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

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

.section-alt {
    background-color: var(--bg-alt);
}

.section-title {
    font-family: var(--font-heading);
    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(--secondary-color), var(--accent-color));
    border-radius: 2px;
}

/* ===========================
   Navigation
   =========================== */

#navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: rgba(255, 255, 255, 0.98);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: all var(--transition-normal);
}

#navbar.scrolled {
    background-color: rgba(255, 255, 255, 1);
    box-shadow: var(--shadow-md);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

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

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

.nav-link {
    color: var(--text-color);
    font-weight: 500;
    font-size: 0.95rem;
    position: relative;
    padding: 0.5rem 0;
}

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

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

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

.hamburger span {
    width: 25px;
    height: 3px;
    background-color: var(--primary-color);
    transition: all var(--transition-normal);
}

/* ===========================
   Hero Section
   =========================== */

.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding-top: 70px;
    position: relative;
    background: linear-gradient(135deg, #f5f7fa 0%, #ffffff 50%, #f0f4f8 100%);
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 4rem;
    align-items: center;
}

.hero-text {
    animation: fadeInUp 1s ease;
}

.hero-title {
    font-family: var(--font-heading);
    font-size: 4rem;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-light);
    margin-bottom: 1.5rem;
    font-weight: 400;
}

.hero-description {
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--text-color);
    margin-bottom: 2rem;
    max-width: 600px;
}

.hero-links {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.875rem 1.75rem;
    border-radius: 50px;
    font-weight: 500;
    font-size: 1rem;
    transition: all var(--transition-normal);
    cursor: pointer;
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    background-color: #2980b9;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background-color: transparent;
    color: var(--secondary-color);
    border-color: var(--secondary-color);
}

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

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

.social-links a {
    width: 45px;
    height: 45px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: var(--bg-alt);
    color: var(--primary-color);
    font-size: 1.25rem;
    transition: all var(--transition-normal);
}

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

.hero-image {
    display: flex;
    justify-content: center;
    align-items: center;
    animation: fadeIn 1.5s ease;
}

.profile-placeholder {
    width: 300px;
    height: 300px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--secondary-color), var(--accent-color));
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-lg);
}

.profile-placeholder i {
    font-size: 8rem;
    color: white;
    opacity: 0.9;
}

.profile-photo {
    width: 300px;
    height: 300px;
    border-radius: 50%;
    object-fit: cover;
    box-shadow: var(--shadow-lg);
    border: 5px solid white;
}

.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    animation: bounce 2s infinite;
}

.scroll-indicator a {
    color: var(--primary-color);
    font-size: 2rem;
}

/* ===========================
   About Section
   =========================== */

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

.about-text {
    font-size: 1.1rem;
    line-height: 1.8;
}

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

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

.stat-item {
    text-align: center;
    padding: 2rem;
    background-color: white;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
}

.stat-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--secondary-color);
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 0.95rem;
    color: var(--text-light);
    font-weight: 500;
}

/* ===========================
   Education Section
   =========================== */

.timeline {
    max-width: 900px;
    margin: 0 auto;
    position: relative;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 30px;
    top: 0;
    bottom: 0;
    width: 3px;
    background: linear-gradient(180deg, var(--secondary-color), var(--accent-color));
}

.timeline-item {
    position: relative;
    padding-left: 80px;
    margin-bottom: 3rem;
}

.timeline-marker {
    position: absolute;
    left: 18px;
    top: 8px;
    width: 25px;
    height: 25px;
    border-radius: 50%;
    background-color: var(--secondary-color);
    border: 4px solid white;
    box-shadow: var(--shadow-sm);
    z-index: 1;
}

.timeline-content {
    background-color: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
}

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

.timeline-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 0.75rem;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.timeline-header h3 {
    font-size: 1.5rem;
    color: var(--primary-color);
    flex: 1;
}

.timeline-date {
    color: var(--text-light);
    font-size: 0.9rem;
    font-weight: 500;
    white-space: nowrap;
}

.timeline-subtitle {
    font-size: 1.1rem;
    color: var(--secondary-color);
    font-weight: 500;
    margin-bottom: 1rem;
}

.timeline-details {
    list-style: none;
    padding-left: 0;
}

.timeline-details li {
    padding: 0.5rem 0;
    padding-left: 1.5rem;
    position: relative;
}

.timeline-details li::before {
    content: '▸';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
}

/* ===========================
   Research Section
   =========================== */

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(450px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.research-card {
    background-color: white;
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
    border-left: 4px solid var(--secondary-color);
}

.research-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.research-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1.5rem;
}

.research-icon {
    width: 60px;
    height: 60px;
    border-radius: 12px;
    background: linear-gradient(135deg, var(--secondary-color), var(--accent-color));
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.75rem;
}

.research-meta {
    text-align: right;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.research-status {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background-color: #fff3cd;
    color: #856404;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
}

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

.research-title {
    font-size: 1.35rem;
    margin-bottom: 0.75rem;
    color: var(--primary-color);
    line-height: 1.4;
}

.research-role {
    color: var(--secondary-color);
    font-size: 1rem;
    margin-bottom: 1rem;
}

.research-details {
    list-style: none;
    padding-left: 0;
    margin-bottom: 1.5rem;
}

.research-details li {
    padding: 0.75rem 0;
    padding-left: 1.5rem;
    position: relative;
    line-height: 1.6;
}

.research-details li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--secondary-color);
    font-size: 1.5rem;
    line-height: 1;
}

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

.research-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.625rem 1.25rem;
    background-color: var(--bg-alt);
    color: var(--secondary-color);
    border-radius: 6px;
    font-weight: 500;
    font-size: 0.95rem;
    transition: all var(--transition-normal);
}

.research-link:hover {
    background-color: var(--secondary-color);
    color: white;
}

/* ===========================
   Skills Section
   =========================== */

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.skill-category {
    background-color: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
    text-align: center;
}

.skill-category:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
}

.skill-icon {
    width: 70px;
    height: 70px;
    margin: 0 auto 1.5rem;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--secondary-color), var(--accent-color));
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 2rem;
}

.skill-category h3 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    color: var(--primary-color);
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    justify-content: center;
}

.skill-tag {
    display: inline-block;
    padding: 0.5rem 1rem;
    background-color: var(--bg-alt);
    color: var(--text-color);
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all var(--transition-fast);
}

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

/* ===========================
   Activities Section
   =========================== */

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

.activity-card {
    background-color: white;
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
}

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

.activity-icon {
    width: 60px;
    height: 60px;
    border-radius: 12px;
    background: linear-gradient(135deg, var(--secondary-color), var(--accent-color));
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.75rem;
    margin-bottom: 1.5rem;
}

.activity-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.activity-subtitle {
    color: var(--secondary-color);
    font-weight: 500;
    font-size: 1.05rem;
    margin-bottom: 1rem;
}

.activity-card p {
    line-height: 1.7;
    color: var(--text-color);
}

.additional-info {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.info-item {
    background-color: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    display: flex;
    align-items: flex-start;
    gap: 1.5rem;
}

.info-item i {
    font-size: 2rem;
    color: var(--secondary-color);
    min-width: 40px;
}

.info-item h4 {
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

.info-item p {
    margin-bottom: 0;
    line-height: 1.6;
}

/* ===========================
   Contact Section
   =========================== */

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

.contact-intro {
    font-size: 1.1rem;
    line-height: 1.8;
    margin-bottom: 3rem;
    color: var(--text-color);
}

.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 2rem;
}

.contact-card {
    background-color: white;
    padding: 2.5rem 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-normal);
    display: flex;
    flex-direction: column;
    align-items: center;
    color: var(--text-color);
}

.contact-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    background-color: var(--secondary-color);
    color: white;
}

.contact-card i {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: var(--secondary-color);
    transition: color var(--transition-normal);
}

.contact-card:hover i {
    color: white;
}

.contact-card h3 {
    font-size: 1.25rem;
    margin-bottom: 0.75rem;
    color: var(--primary-color);
    transition: color var(--transition-normal);
}

.contact-card:hover h3 {
    color: white;
}

.contact-card p {
    margin-bottom: 0.25rem;
    font-size: 0.95rem;
}

.contact-alt {
    font-size: 0.85rem;
    opacity: 0.8;
}

/* ===========================
   Footer
   =========================== */

.footer {
    background-color: var(--primary-color);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

.footer p {
    margin-bottom: 0.5rem;
}

.footer-update {
    font-size: 0.9rem;
    opacity: 0.8;
}

/* ===========================
   Animations
   =========================== */

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

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

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

.fade-in {
    animation: fadeIn 1s ease;
}

/* ===========================
   Responsive Design
   =========================== */

@media screen and (max-width: 968px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-text {
        order: 2;
    }
    
    .hero-image {
        order: 1;
        margin-bottom: 2rem;
    }
    
    .hero-title {
        font-size: 3rem;
    }
    
    .hero-links {
        justify-content: center;
    }
    
    .social-links {
        justify-content: center;
    }
    
    .research-grid {
        grid-template-columns: 1fr;
    }
    
    .stats {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: left var(--transition-normal);
        box-shadow: var(--shadow-md);
        padding: 2rem 0;
        gap: 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .nav-link {
        padding: 1rem;
        width: 100%;
        display: block;
    }
    
    .hamburger {
        display: flex;
    }
    
    .hamburger.active span:nth-child(1) {
        transform: rotate(45deg) translate(8px, 8px);
    }
    
    .hamburger.active span:nth-child(2) {
        opacity: 0;
    }
    
    .hamburger.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -7px);
    }
}

@media screen and (max-width: 768px) {
    html {
        font-size: 14px;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .container {
        padding: 0 1.5rem;
    }
    
    .section {
        padding: 4rem 0;
    }
    
    .profile-placeholder {
        width: 220px;
        height: 220px;
    }
    
    .profile-placeholder i {
        font-size: 6rem;
    }
    
    .profile-photo {
        width: 220px;
        height: 220px;
    }
    
    .timeline::before {
        left: 15px;
    }
    
    .timeline-item {
        padding-left: 50px;
    }
    
    .timeline-marker {
        left: 7px;
        width: 18px;
        height: 18px;
    }
    
    .activities-grid {
        grid-template-columns: 1fr;
    }
    
    .skills-grid {
        grid-template-columns: 1fr;
    }
    
    .contact-grid {
        grid-template-columns: 1fr;
    }
}

@media screen and (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-links {
        flex-direction: column;
        width: 100%;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    .research-card {
        padding: 1.5rem;
    }
    
    .timeline-content {
        padding: 1.5rem;
    }
}

/* ===========================
   Print Styles
   =========================== */

@media print {
    .nav-menu,
    .hamburger,
    .scroll-indicator,
    .hero-links,
    .social-links {
        display: none;
    }
    
    .section {
        page-break-inside: avoid;
    }
}