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

:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --text-color: #333;
    --text-light: #666;
    --background-color: #ffffff;
    --light-gray: #f8f9fa;
    --border-color: #e9ecef;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 5px 20px rgba(0, 0, 0, 0.15);
    --transition: all 0.3s ease;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    text-align: center;
    margin-bottom: 2rem;
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--secondary-color), var(--accent-color));
    border-radius: 2px;
}

/* Loading Screen */
#loading-screen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--background-color);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 9999;
    transition: opacity 0.5s ease;
}

.loading-spinner {
    width: 50px;
    height: 50px;
    border: 3px solid var(--light-gray);
    border-top: 3px solid var(--secondary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 20px;
}

@keyframes spin {
    0% {
        transform: rotate(0deg);
    }

    100% {
        transform: rotate(360deg);
    }
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow);
    z-index: 1000;
    transition: var(--transition);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    max-width: 1200px;
    margin: 0 auto;
}

.nav-logo h2 {
    color: var(--primary-color);
    font-size: 1.5rem;
    font-weight: 700;
}

.nav-logo p {
    color: var(--text-light);
    font-size: 0.9rem;
    margin-top: 0.2rem;
}

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

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

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--secondary-color);
    transition: var(--transition);
}

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

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

.bar {
    width: 25px;
    height: 3px;
    background: var(--primary-color);
    margin: 3px 0;
    transition: var(--transition);
}


/* About Section */
.about {
    padding-top: 110px;
    padding-bottom: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    background: var(--light-gray);
}

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

.about-image {
    text-align: center;
}

.profile-img {
    width: 300px;
    height: auto;
    border-radius: 10px;
    object-fit: cover;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

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

.about-text p {
    margin-bottom: 1rem;
    font-size: 1.1rem;
    line-height: 1.7;
    color: var(--text-light);
}

.education,
.additional-info {
    margin-top: 2rem;
    padding: 1.5rem;
    background: white;
    border-radius: 10px;
    box-shadow: var(--shadow);
}

.education h3,
.additional-info h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.education ul {
    list-style: none;
}

.education li {
    margin-bottom: 0.8rem;
    padding-left: 1rem;
    position: relative;
}

.education li::before {
    content: '▶';
    color: var(--secondary-color);
    position: absolute;
    left: 0;
}

.quick-fact {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.8rem 0;
    border-bottom: 1px solid var(--border-color);
}

.quick-fact:last-child {
    border-bottom: none;
}

.quick-fact-label {
    font-weight: 600;
    color: var(--primary-color);
}

.quick-fact-value {
    color: var(--text-light);
}

/* Research Section */
.research {
    padding: 100px 0;
}

.research-interests {
    margin-bottom: 4rem;
}

.research-interests h3 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 2rem;
    text-align: center;
}

.interests-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.interest-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    text-align: center;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

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

.interest-card i {
    font-size: 3rem;
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

.interest-card h4 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.3rem;
}

.publications h3 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 2rem;
    text-align: center;
}

.publication-list {
    max-width: 800px;
    margin: 0 auto;
}

.publication-item {
    background: transparent;
    padding: 0;
    margin-bottom: 2rem;
    border-radius: 0;
    box-shadow: none;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1.5rem;
}

.publication-item:hover {
    box-shadow: none;
}

.publication-item.featured {
    border-left: none;
    position: relative;
}

.publication-item.featured::before {
    content: '★ Featured';
    display: inline-block;
    background: var(--accent-color);
    color: white;
    padding: 0.2rem 0.5rem;
    border-radius: 4px;
    font-size: 0.7rem;
    margin-bottom: 0.5rem;
}

.publication-content {
    line-height: 1.6;
}

.pub-title strong {
    color: var(--primary-color);
    font-size: 1.1rem;
}

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

.venue {
    color: var(--text-light);
}

.publication-links-inline {
    display: inline-block;
    margin-left: 0.5rem;
}

.pub-link {
    background: transparent;
    color: var(--secondary-color);
    padding: 0 5px;
    text-decoration: none;
    border-radius: 0;
    font-size: 0.95rem;
    border: 1px solid var(--secondary-color);
    border-radius: 4px;
    margin-right: 5px;
}

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

/* Teaching Section */
.teaching {
    padding: 100px 0;
    background: var(--light-gray);
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.course-card {
    background: white;
    padding: 2rem;
    border-radius: 15px;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

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

.course-card.current {
    border-top: 4px solid var(--secondary-color);
}

.course-card.past {
    opacity: 0.8;
}

.course-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1rem;
}

.course-card h4 {
    color: var(--primary-color);
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
}

.course-level {
    background: var(--light-gray);
    color: var(--text-color);
    padding: 0.3rem 0.8rem;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 600;
}

.semester {
    color: var(--secondary-color);
    font-weight: 600;
    margin-bottom: 1rem;
}

.course-info {
    display: flex;
    gap: 2rem;
    margin-top: 1rem;
    color: var(--text-light);
    font-size: 0.9rem;
    flex-wrap: wrap;
}



/* Projects Section */
.projects {
    padding: 100px 0;
}

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

.project-card {
    background: white;
    border-radius: 15px;
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: var(--transition);
}

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

.project-card.featured {
    border-top: 4px solid var(--accent-color);
}

.project-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem 2rem 1rem;
}

.project-header h3 {
    color: var(--primary-color);
    font-size: 1.3rem;
}

.project-status {
    padding: 0.3rem 1rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
}

.project-status.active {
    background: #d4edda;
    color: #155724;
}

.project-status.completed {
    background: #cce5ff;
    color: #004085;
}

.project-card p {
    padding: 0 2rem;
    color: var(--text-light);
    line-height: 1.6;
}

.project-tech {
    padding: 1rem 2rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tech-tag {
    background: var(--light-gray);
    color: var(--text-color);
    padding: 0.3rem 0.8rem;
    border-radius: 15px;
    font-size: 0.8rem;
}

.project-links {
    padding: 1rem 2rem 2rem;
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.project-link {
    background: var(--secondary-color);
    color: white;
    padding: 0.6rem 1.2rem;
    text-decoration: none;
    border-radius: 5px;
    font-size: 0.9rem;
    transition: var(--transition);
}

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

.project-funding {
    padding: 0 2rem 1rem;
    font-size: 0.9rem;
    color: var(--text-light);
    font-style: italic;
}



.social-grid {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-top: 2rem;
    flex-wrap: wrap;
}

.social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 45px;
    height: 45px;
    border-radius: 50%;
    background: white;
    color: var(--primary-color);
    text-decoration: none;
    box-shadow: var(--shadow);
    transition: all 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    position: relative;
    font-size: 1.2rem;
}

.social-link span {
    display: none;
}

.social-link:hover {
    background: var(--secondary-color);
    color: white;
    transform: translateY(-5px) scale(1.1);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
}

/* Tooltip Styling */
.social-link::before {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    background: #333;
    color: white;
    padding: 0.4rem 0.8rem;
    border-radius: 5px;
    font-size: 0.8rem;
    white-space: nowrap;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    pointer-events: none;
    margin-bottom: 10px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    z-index: 10;
}

.social-link::after {
    content: '';
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%) translateY(10px);
    border: 6px solid transparent;
    border-top-color: #333;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    pointer-events: none;
    margin-bottom: -2px;
    z-index: 10;
}

.social-link:hover::before,
.social-link:hover::after {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}

.social-link i {
    font-size: 1.2rem;
    transition: transform 0.3s ease;
}

.social-link:hover i {
    transform: scale(1.1);
}

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

.footer p {
    margin-bottom: 0.5rem;
    opacity: 0.8;
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }

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

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background: white;
        width: 100%;
        text-align: center;
        transition: var(--transition);
        box-shadow: var(--shadow);
        padding: 2rem 0;
    }

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

    .nav-toggle {
        display: flex;
    }

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

    .nav-toggle.active .bar:nth-child(1) {
        transform: translateY(8px) rotate(45deg);
    }

    .nav-toggle.active .bar:nth-child(3) {
        transform: translateY(-8px) rotate(-45deg);
    }



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

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

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

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



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

    .contact-content {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

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

    .container {
        padding: 0 15px;
    }

    .nav-container {
        padding: 1rem 15px;
    }

    .course-info {
        flex-direction: column;
        gap: 0.5rem;
    }

    .project-links {
        flex-direction: column;
    }

    .publication-links {
        flex-wrap: wrap;
    }
}

@media (max-width: 480px) {


    .profile-img {
        width: 200px;
        height: 200px;
    }



    .interest-card,
    .course-card,
    .project-card {
        padding: 1.5rem;
    }
}

/* Smooth scrolling */
html {
    scroll-behavior: smooth;
}

/* Focus styles for accessibility */
.nav-link:focus,
.cta-button:focus,
.project-link:focus,
.social-link:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 2px;
}

/* Print styles */
@media print {

    .navbar,
    .hero,
    .footer {
        display: none;
    }

    .section-title {
        color: black;
        page-break-after: avoid;
    }

    .publication-item,
    .project-card,
    .course-card {
        page-break-inside: avoid;
        box-shadow: none;
        border: 1px solid #ccc;
    }
}

/* Image Slider */
.image-slider-container {
    position: relative;
    width: 300px;
    margin: 0 auto;
    overflow: hidden;
    border-radius: 10px;
    /* Prevent default image drag */
    user-select: none;
    -webkit-user-select: none;
}

.profile-img {
    /* Existing style override */
    width: 100%;
    display: block;
    pointer-events: none;
    /* Let the container handle drag events */
    transition: transform 0.3s ease, opacity 0.3s ease;
}

.profile-img.slide-anim {
    transition: transform 0.3s ease-out;
}

.slider-dots {
    position: absolute;
    bottom: 15px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 8px;
    z-index: 10;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.image-slider-container:hover .slider-dots {
    opacity: 1;
}

.slider-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background-color: rgba(255, 255, 255, 0.5);
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
}

.slider-dot.active {
    background-color: white;
    transform: scale(1.2);
    width: 10px;
}

/* Slider Arrows */
.slider-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: rgba(255, 255, 255, 0.7);
    color: var(--primary-color);
    border: none;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    font-size: 1.2rem;
    cursor: pointer;
    z-index: 10;
    display: flex;
    /* Flex to center the icon */
    align-items: center;
    justify-content: center;
    opacity: 0;
    transition: all 0.3s ease;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
    /* Prevent selection of arrow text */
    user-select: none;
}

.image-slider-container:hover .slider-arrow {
    opacity: 1;
}

.slider-arrow:hover {
    background: white;
    transform: translateY(-50%) scale(1.1);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
}

.prev-arrow {
    left: 10px;
    padding-right: 2px;
    /* Visual optical adjustment for the character */
}

.next-arrow {
    right: 10px;
    padding-left: 2px;
    /* Visual optical adjustment */
}

/* Hide arrows on touch devices to avoid clutter, or maybe keep them? 
   Let's keep them as requested for "easy mouse button", 
   but maybe make them slightly larger on mobile if needed.
   For now standard size is fine. */
/* Slider Track Refactoring */
.image-slider-container {
    width: 100%;
    max-width: 300px;
    aspect-ratio: 3/4;
    height: auto;
    margin: 0 auto;
    overflow: hidden;
    /* Hide overflow images */
    border-radius: 10px;
    position: relative;
    user-select: none;
    -webkit-user-select: none;
    box-shadow: var(--shadow);
}

.slider-track {
    display: flex;
    /* Horizontal alignment */
    width: 100%;
    height: 100%;
    transition: transform 0.3s ease-in-out;
    /* Smooth slide */
}

.profile-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center top;
    flex-shrink: 0;
    /* Do not shrink */
    pointer-events: none;
    /* Remove old transition/opacity stuff */
    transition: none;
    opacity: 1;
}

/* Ensure arrows and dots stay on top */
.slider-arrow,
.slider-dots {
    z-index: 20;
}