/* ================================
   CSS Variables for Easy Customization
   ================================ */
:root {
    /* Primary Colors */
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;

    /* Accent Colors */
    --accent-color: #ec4899;
    --accent-dark: #db2777;

    /* Background Colors */
    --bg-primary: #ffffff;
    --bg-secondary: #f9fafb;
    --bg-tertiary: #f3f4f6;

    /* Text Colors */
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --text-tertiary: #9ca3af;

    /* Border Colors */
    --border-color: #e5e7eb;
    --border-dark: #d1d5db;

    /* Shadow */
    --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);

    /* Spacing */
    --section-padding: 80px;
    --container-max-width: 1200px;

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;

    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
}

/* Dark Mode Variables */
[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;

    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-tertiary: #94a3b8;

    --border-color: #334155;
    --border-dark: #475569;

    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4), 0 2px 4px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4), 0 4px 6px -2px rgba(0, 0, 0, 0.3);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.4), 0 10px 10px -5px rgba(0, 0, 0, 0.3);
}

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

html {
    scroll-behavior: smooth;
    overflow-x: hidden;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
        sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color var(--transition-normal), color var(--transition-normal);
    overflow-x: hidden;
    width: 100%;
}

/* ================================
   Utility Classes
   ================================ */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 20px;
}

.section {
    min-height: 100vh;
    padding: 50px 0 50px 0;
    display: flex;
    align-items: flex-start;
    overflow-x: hidden;
    width: 100%;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 1rem;
    margin-top: 0;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.125rem;
    margin-bottom: 3rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.gradient-text {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Fade-in animation classes */
.fade-in {
    opacity: 0;
    transform: translateY(30px);
    animation: fadeInUp 0.8s ease forwards;
}

.fade-in:nth-child(1) { animation-delay: 0.1s; }
.fade-in:nth-child(2) { animation-delay: 0.2s; }
.fade-in:nth-child(3) { animation-delay: 0.3s; }
.fade-in:nth-child(4) { animation-delay: 0.4s; }

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

/* ================================
   Navigation Bar
   ================================ */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: var(--bg-primary);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: all var(--transition-normal);
}

.navbar.scrolled {
    box-shadow: var(--shadow-md);
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.9);
}

[data-theme="dark"] .navbar.scrolled {
    background-color: rgba(15, 23, 42, 0.9);
}

.nav-container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 1rem 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    transition: transform var(--transition-fast);
}

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

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

.nav-link {
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    position: relative;
    transition: color var(--transition-fast);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    transition: width var(--transition-normal);
}

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

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

/* Theme Toggle Button */
.theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-primary);
    transition: transform var(--transition-fast);
}

.theme-toggle:hover {
    transform: rotate(20deg);
}

.sun-icon {
    display: none;
}

.moon-icon {
    display: block;
}

[data-theme="dark"] .sun-icon {
    display: block;
}

[data-theme="dark"] .moon-icon {
    display: none;
}

/* Hamburger Menu */
.hamburger {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
    gap: 0.25rem;
}

.bar {
    width: 25px;
    height: 3px;
    background-color: var(--text-primary);
    transition: all var(--transition-normal);
    border-radius: 3px;
}

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

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

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

/* ================================
   Hero Section
   ================================ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding-top: 80px;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.1) 0%, transparent 70%);
    top: -250px;
    right: -250px;
    border-radius: 50%;
}

.hero::after {
    content: '';
    position: absolute;
    width: 400px;
    height: 400px;
    background: radial-gradient(circle, rgba(236, 72, 153, 0.1) 0%, transparent 70%);
    bottom: -200px;
    left: -200px;
    border-radius: 50%;
}

.hero-container {
    text-align: center;
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.5rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-weight: 500;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

/* Scroll Indicator */
.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
}

.mouse {
    width: 26px;
    height: 40px;
    border: 2px solid var(--text-tertiary);
    border-radius: 15px;
    position: relative;
}

.wheel {
    width: 4px;
    height: 8px;
    background: var(--text-tertiary);
    border-radius: 2px;
    position: absolute;
    top: 8px;
    left: 50%;
    transform: translateX(-50%);
    animation: scroll 1.5s infinite;
}

@keyframes scroll {
    0% {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }
    100% {
        opacity: 0;
        transform: translateX(-50%) translateY(12px);
    }
}

/* ================================
   Buttons
   ================================ */
.btn {
    display: inline-block;
    padding: 0.75rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    text-decoration: none;
    border-radius: var(--radius-md);
    transition: all var(--transition-normal);
    cursor: pointer;
    border: 2px solid transparent;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
}

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

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

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

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

.btn-outline:hover {
    background: var(--bg-tertiary);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

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

.about-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 3rem;
    align-items: center;
}

.about-image {
    display: flex;
    justify-content: center;
}

.image-placeholder {
    width: 250px;
    height: 250px;
    border-radius: 50%;
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    transition: transform var(--transition-normal);
}

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

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

.about-text p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
    font-size: 1.05rem;
    line-height: 1.8;
}

.about-text .btn {
    margin-top: 1.5rem;
}

.about-buttons {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
    flex-wrap: wrap;
}

.about-contact-links {
    display: flex;
    gap: 1rem;
    margin-top: 2rem;
    justify-content: center;
}

.about-contact-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--bg-primary);
    border: 2px solid var(--border-color);
    color: var(--primary-color);
    transition: all var(--transition-normal);
    text-decoration: none;
}

.about-contact-icon:hover {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.about-contact-icon svg {
    flex-shrink: 0;
}

/* ================================
   Projects Section
   ================================ */
.projects {
    background-color: var(--bg-primary);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.project-card {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-color);
}

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

.project-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1rem;
}

.project-icon {
    color: var(--primary-color);
}

.project-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.project-description {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.7;
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.tech-tag {
    background: var(--bg-tertiary);
    color: var(--primary-color);
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-sm);
    font-size: 0.875rem;
    font-weight: 500;
    border: 1px solid var(--border-color);
}

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

.project-link {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    transition: color var(--transition-fast);
}

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

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

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

.skill-category {
    background: var(--bg-primary);
    padding: 2rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
}

.skill-category:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.skill-category-title {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.skill-category-title svg {
    color: var(--primary-color);
}

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

.skill-tag {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-md);
    font-size: 0.9rem;
    font-weight: 500;
    transition: all var(--transition-fast);
    cursor: default;
}

.skill-tag:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-md);
}

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

.contact-subtitle {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.125rem;
    margin-bottom: 3rem;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.contact-links {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    max-width: 600px;
    margin: 0 auto;
}

.contact-link {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1.5rem;
    background: var(--bg-primary);
    border-radius: var(--radius-md);
    text-decoration: none;
    color: var(--text-primary);
    transition: all var(--transition-normal);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-md);
    word-wrap: break-word;
    overflow-wrap: break-word;
}

.contact-link:hover {
    background: var(--bg-secondary);
    border-color: var(--primary-color);
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.contact-link svg {
    flex-shrink: 0;
    color: var(--primary-color);
}

/* ================================
   Footer
   ================================ */
.footer {
    background-color: var(--bg-secondary);
    padding: 2rem 0;
    border-top: 1px solid var(--border-color);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.footer-content p {
    color: var(--text-secondary);
}

.footer-links {
    display: flex;
    gap: 1.5rem;
}

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

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

/* ================================
   Responsive Design
   ================================ */
@media (max-width: 768px) {
    /* Navigation */
    .hamburger {
        display: flex;
    }

    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: var(--bg-primary);
        width: 100%;
        text-align: center;
        transition: left var(--transition-normal);
        box-shadow: var(--shadow-lg);
        padding: 2rem 0;
        gap: 1rem;
    }

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

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

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

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

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

    /* About */
    .about-content {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .about-contact-icon {
        width: 40px;
        height: 40px;
    }

    /* Container */
    .container {
        padding: 0 15px;
        max-width: 100%;
    }

    /* Publications */
    .publication-card {
        grid-template-columns: 60px 1fr;
        gap: 1rem;
        padding: 1rem;
    }

    .publication-year {
        font-size: 1rem;
    }

    .publication-title {
        font-size: 1.1rem;
    }

    /* Skills */
    .skills-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    /* Certifications */
    .certifications-grid-two-col {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .certification-card {
        padding: 1.25rem;
    }

    .cert-icon svg {
        width: 28px;
        height: 28px;
    }

    .cert-link {
        width: 100%;
        justify-content: center;
        margin-top: 0.5rem;
    }

    /* Research */
    .research-grid {
        grid-template-columns: 1fr;
    }

    /* Timeline */
    .timeline {
        padding-left: 20px;
        max-width: 100%;
    }

    .timeline::before {
        left: 5px;
    }

    .timeline-item {
        padding-left: 15px;
    }

    .timeline-content {
        padding: 1.5rem;
    }

    /* Contact */
    .contact-link {
        padding: 1rem;
        gap: 0.75rem;
    }

    .contact-link span {
        word-break: break-word;
    }

    /* Footer */
    .footer-content {
        flex-direction: column;
        text-align: center;
    }

    /* Section padding */
    .section {
        padding: 60px 0;
    }

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

@media (max-width: 480px) {
    .container {
        padding: 0 10px;
    }

    .hero-title {
        font-size: 1.75rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .section-title {
        font-size: 1.75rem;
    }

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

    .skills-grid {
        grid-template-columns: 1fr;
    }

    .certification-card {
        flex-direction: column;
        padding: 1rem;
    }

    .cert-icon svg {
        width: 24px;
        height: 24px;
    }

    .cert-title {
        font-size: 1rem;
    }

    .publication-card {
        grid-template-columns: 1fr;
        gap: 1rem;
        padding: 0.75rem;
    }

    .publication-year {
        font-size: 1rem;
        padding-bottom: 0.5rem;
        border-bottom: 2px solid var(--primary-color);
    }

    .publication-title {
        font-size: 1rem;
    }

    .timeline {
        padding-left: 15px;
    }

    .timeline-content {
        padding: 1rem;
    }

    .timeline-title {
        font-size: 1.25rem;
    }

    .contact-link {
        padding: 0.75rem;
    }
}

/* ================================
   Scroll Animations
   ================================ */
.scroll-reveal {
    opacity: 0;
    transform: translateY(50px);
    transition: all 0.6s ease;
}

.scroll-reveal.active {
    opacity: 1;
    transform: translateY(0);
}

/* ================================
   Custom Scrollbar
   ================================ */
::-webkit-scrollbar {
    width: 10px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-dark);
}

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

.publications-list {
    max-width: 900px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.publication-card {
    display: grid;
    grid-template-columns: 80px 1fr;
    gap: 2rem;
    background: var(--bg-primary);
    padding: 2rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
}

.publication-card:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.publication-card.preprint {
    border-left: 4px solid var(--accent-color);
}

.publication-year {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
    padding-top: 0.25rem;
}

.publication-content {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.publication-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.4;
    word-wrap: break-word;
    overflow-wrap: break-word;
}

.publication-authors {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.publication-authors strong {
    color: var(--text-primary);
}

.publication-venue {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.publication-abstract {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-top: 0.5rem;
    word-wrap: break-word;
    overflow-wrap: break-word;
}

.publication-links {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    align-items: center;
    margin-top: 0.5rem;
}

.pub-link {
    display: flex;
    align-items: center;
    gap: 0.4rem;
    color: var(--primary-color);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all var(--transition-fast);
    padding: 0.25rem 0.5rem;
    border-radius: var(--radius-sm);
}

.pub-link:hover {
    background: var(--bg-tertiary);
    transform: translateY(-2px);
}

.publication-badge {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-sm);
    font-size: 0.8rem;
    font-weight: 600;
}

.preprint-badge {
    background: linear-gradient(135deg, var(--accent-color) 0%, var(--accent-dark) 100%);
}

/* ================================
   Research & Teaching Section
   ================================ */
.research {
    background-color: var(--bg-primary);
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
}

.research-card {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
}

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

.research-icon {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    display: flex;
    justify-content: center;
}

.research-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    text-align: center;
}

.research-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.research-list li {
    color: var(--text-secondary);
    line-height: 1.6;
    padding-left: 1.5rem;
    position: relative;
}

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

.research-list strong {
    color: var(--text-primary);
}

/* ================================
   Education & Experience Sections (Timeline)
   ================================ */
.education {
    background-color: var(--bg-secondary);
}

.experience {
    background-color: var(--bg-primary);
}

.timeline {
    max-width: 900px;
    margin: 0 auto;
    position: relative;
    padding-left: 50px;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 0;
    bottom: 0;
    width: 3px;
    background: linear-gradient(180deg, var(--primary-color) 0%, var(--accent-color) 100%);
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
    padding-left: 30px;
}

.timeline-content {
    background: var(--bg-primary);
    padding: 2rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
    word-wrap: break-word;
    overflow-wrap: break-word;
    max-width: 100%;
}

.experience .timeline-content {
    background: var(--bg-secondary);
}

.timeline-content:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.timeline-date {
    display: inline-block;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    color: white;
    padding: 0.4rem 1rem;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.timeline-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

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

.timeline-description {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 0.5rem;
}

.timeline-list {
    list-style: none;
    margin-top: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.timeline-list li {
    color: var(--text-secondary);
    line-height: 1.6;
    padding-left: 1.5rem;
    position: relative;
}

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

/* ================================
   Certifications Section
   ================================ */
.certifications {
    background-color: var(--bg-primary);
}

.cert-category-title {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-top: 2.5rem;
    margin-bottom: 1.5rem;
    text-align: center;
}

.cert-category-title:first-of-type {
    margin-top: 0;
}

.certifications-grid {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    max-width: 900px;
    margin: 0 auto;
}

.certifications-grid-two-col {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
    max-width: 1200px;
    margin: 0 auto;
}

.certification-card {
    background: var(--bg-primary);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: 1rem;
}

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

.cert-icon {
    color: var(--primary-color);
    flex-shrink: 0;
}

.cert-icon svg {
    width: 32px;
    height: 32px;
}

.cert-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.cert-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.4;
    margin-bottom: 0.25rem;
}

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

.cert-date {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.cert-id {
    color: var(--text-tertiary);
    font-size: 0.8rem;
    font-family: monospace;
}

.cert-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.85rem;
    padding: 0.5rem 1rem;
    border: 2px solid var(--primary-color);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
    flex-shrink: 0;
    align-self: flex-start;
}

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

/* ================================
   Print Styles
   ================================ */
@media print {
    .navbar,
    .scroll-indicator,
    .theme-toggle,
    .hamburger {
        display: none;
    }

    .section {
        page-break-inside: avoid;
    }
}

/* ================================
   Research Carousel Section
   ================================ */
.research-carousel {
    background: var(--bg-primary);
    padding: var(--section-padding) 0;
}

.research-carousel .container {
    width: 100%;
}

.carousel-container {
    position: relative;
    width: 100%;
    max-width: var(--container-max-width);
    margin: 0 auto;
    overflow: hidden;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl);
}

.carousel-slides {
    position: relative;
    width: 100%;
    height: 650px;
    display: flex;
}

.carousel-slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transform: translateX(100%);
    transition: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
    pointer-events: none;
}

.carousel-slide.active {
    opacity: 1;
    transform: translateX(0);
    pointer-events: auto;
    z-index: 2;
}

.carousel-slide.prev {
    transform: translateX(-100%);
}

.slide-content {
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    background: var(--bg-primary);
    border-radius: var(--radius-xl);
    overflow: hidden;
}

.slide-image {
    width: 100%;
    height: 75%;
    object-fit: contain;
    background: linear-gradient(135deg, var(--bg-tertiary) 0%, var(--bg-secondary) 100%);
}

.slide-info {
    padding: 2rem;
    padding-bottom: 4rem;
    background: var(--bg-primary);
    border-top: 3px solid var(--primary-color);
}

.slide-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.slide-description {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.6;
    margin-bottom: 1rem;
}

/* Navigation Arrows */
.carousel-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.9);
    border: none;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10;
    transition: all var(--transition-normal);
    box-shadow: var(--shadow-lg);
}

[data-theme="dark"] .carousel-arrow {
    background: rgba(30, 41, 59, 0.9);
}

.carousel-arrow:hover {
    background: var(--primary-color);
    transform: translateY(-50%) scale(1.1);
}

.carousel-arrow:hover svg {
    stroke: white;
}

.carousel-arrow-left {
    left: 20px;
}

.carousel-arrow-right {
    right: 20px;
}

.carousel-arrow svg {
    stroke: var(--text-primary);
    transition: stroke var(--transition-normal);
}

/* Dot Indicators */
.carousel-dots {
    position: absolute;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 12px;
    z-index: 10;
}

.carousel-dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: rgba(99, 102, 241, 0.3);
    border: 2px solid rgba(99, 102, 241, 0.6);
    cursor: pointer;
    transition: all var(--transition-normal);
    padding: 0;
}

[data-theme="dark"] .carousel-dot {
    background: rgba(129, 140, 248, 0.3);
    border-color: rgba(129, 140, 248, 0.6);
}

.carousel-dot:hover {
    transform: scale(1.2);
    background: rgba(99, 102, 241, 0.5);
    border-color: rgba(99, 102, 241, 0.9);
}

[data-theme="dark"] .carousel-dot:hover {
    background: rgba(129, 140, 248, 0.5);
    border-color: rgba(129, 140, 248, 0.9);
}

.carousel-dot.active {
    width: 16px;
    height: 16px;
    background: var(--primary-color);
    border-color: var(--primary-color);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.2);
}

/* Responsive Design */
@media (max-width: 768px) {
    .carousel-slides {
        height: 500px;
    }

    .carousel-arrow {
        width: 40px;
        height: 40px;
    }

    .carousel-arrow-left {
        left: 10px;
    }

    .carousel-arrow-right {
        right: 10px;
    }

    .slide-info {
        padding: 1.5rem;
    }

    .slide-title {
        font-size: 1.25rem;
    }

    .slide-description {
        font-size: 0.9rem;
    }

    .carousel-dots {
        bottom: 15px;
        gap: 8px;
    }

    .carousel-dot {
        width: 10px;
        height: 10px;
    }

    .carousel-dot.active {
        width: 14px;
        height: 14px;
    }
}

@media (max-width: 480px) {
    .carousel-slides {
        height: 400px;
    }

    .slide-image {
        height: 70%;
    }
}