/* Base Styles */
:root {
    --primary-color: #3a7bd5;
    --secondary-color: #00d2ff;
    --dark-color: #333333;
    --light-color: #f4f4f4;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --max-width: 1200px;
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Open Sans', sans-serif;
    line-height: 1.6;
    color: var(--dark-color);
    background-color: #ffffff;
}

h1, h2, h3, h4 {
    font-family: 'Montserrat', sans-serif;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 1rem;
}

h1 {
    font-size: 2.5rem;
}

h2 {
    font-size: 2rem;
    text-align: center;
    margin-bottom: 2rem;
}

h3 {
    font-size: 1.5rem;
}

h4 {
    font-size: 1.2rem;
}

p {
    margin-bottom: 1rem;
}

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

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

ul {
    list-style: none;
}

img {
    width: 100%;
    height: auto;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 2rem;
}

.btn {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    text-decoration: none;
    font-size: 1rem;
    font-family: 'Montserrat', sans-serif;
    font-weight: 600;
    transition: var(--transition);
}

.btn:hover {
    background: var(--secondary-color);
    color: white;
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
}

.section {
    padding: 5rem 0;
}

.section-intro {
    text-align: center;
    max-width: 800px;
    margin: 0 auto 3rem auto;
}

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

/* Navigation Bar */
.navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 100;
    background-color: rgba(255, 255, 255, 0.95);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    transition: var(--transition);
}

.logo a {
    font-family: 'Montserrat', sans-serif;
    font-weight: 700;
    font-size: 1.5rem;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    align-items: center;
}

.nav-links li {
    margin-left: 2rem;
}

.nav-links a {
    color: var(--dark-color);
    font-weight: 600;
}

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

.burger {
    display: none;
    cursor: pointer;
}

.burger div {
    width: 25px;
    height: 3px;
    background-color: var(--dark-color);
    margin: 5px;
    transition: var(--transition);
}

/* Main content spacing to account for fixed navbar */
main {
    margin-top: 80px;
}

/* PDF Display Section */
.pdf-display-container {
    width: 100%;
    height: 80vh;
    display: flex;
    justify-content: center;
    align-items: center;
    margin: 2rem auto;
    border-radius: 10px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    overflow: hidden;
}

.pdf-display {
    width: 100%;
    height: 100%;
    border: none;
}

.pdf-fallback {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    height: 100%;
    background-color: var(--light-color);
    color: var(--dark-color);
    padding: 2rem;
    text-align: center;
}

.pdf-fallback a {
    color: var(--primary-color);
    font-weight: 600;
}

/* About Section */
.about-content {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 2rem;
}

.about-text, .about-image {
    flex: 1 1 400px;
}

.placeholder-image {
    background-color: #e0e0e0;
    height: 300px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-weight: bold;
    color: #999;
    border-radius: 10px;
}

/* Concepts Section */
.cards-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 2rem;
    margin-top: 2rem;
}

.card {
    background-color: white;
    border-radius: 10px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    padding: 2rem;
    flex: 1 1 300px;
    text-align: center;
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.15);
}

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

/* Visualizations Section */
.visualization-container {
    display: flex;
    flex-wrap: wrap;
    gap: 2rem;
    justify-content: center;
}

.visualization {
    flex: 1 1 400px;
    background-color: white;
    border-radius: 10px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    padding: 2rem;
    text-align: center;
}

.vis-canvas {
    margin: 1.5rem 0;
}

.placeholder-vis {
    background-color: #e0e0e0;
    height: 250px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-weight: bold;
    color: #999;
    border-radius: 5px;
}

/* Papers Section */
.paper-container {
    margin-top: 2rem;
}

.paper {
    background-color: white;
    border-radius: 10px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    padding: 2rem;
    transition: var(--transition);
    margin-bottom: 2rem;
}

.paper:last-child {
    margin-bottom: 0;
}

.paper:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.15);
}

.paper h3 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    text-align: center;
}

.paper h3 a {
    color: var(--primary-color);
    text-decoration: none;
    transition: var(--transition);
}

.paper h3 a:hover {
    color: var(--secondary-color);
    text-decoration: underline;
}

.paper-content {
    display: flex;
    flex-wrap: wrap;
    gap: 2rem;
    align-items: center;
}

.paper-info, .paper-image {
    flex: 1 1 400px;
}

.paper-venue {
    font-size: 0.9rem;
    color: var(--secondary-color);
    font-weight: 600;
    margin-bottom: 1rem;
}

.teaser-image {
    max-width: 100%;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    transition: var(--transition);
}

.teaser-image:hover {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    transform: translateY(-2px);
}

/* Video Container for Embedded Videos */
.video-container {
    position: relative;
    padding-bottom: 56.25%; /* 16:9 Aspect Ratio */
    height: 0;
    overflow: hidden;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: 10px;
}

.paper-abstract {
    font-style: italic;
    margin-bottom: 1.5rem;
    line-height: 1.7;
}

.paper-details ul {
    list-style: disc;
    padding-left: 1.5rem;
    margin-top: 0.5rem;
}

.paper-details li {
    margin-bottom: 0.5rem;
}

/* Contact Form */
.contact-form {
    max-width: 600px;
    margin: 0 auto;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 1rem;
    font-family: 'Open Sans', sans-serif;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(58, 123, 213, 0.2);
}

/* Footer */
footer {
    background-color: var(--dark-color);
    color: white;
    padding: 4rem 0 2rem;
}

.footer-content {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-logo, .footer-links, .footer-social {
    flex: 1 1 250px;
}

.footer-logo h3 {
    color: white;
}

.footer-links h4, .footer-social h4 {
    color: white;
    margin-bottom: 1.5rem;
}

.footer-links ul li {
    margin-bottom: 0.75rem;
}

.footer-links a {
    color: #ddd;
}

.footer-links a:hover {
    color: white;
}

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

.social-icons a {
    color: white;
    background-color: rgba(255, 255, 255, 0.1);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: var(--transition);
}

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

.copyright {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    font-size: 0.9rem;
    color: #ddd;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .pdf-display-container {
        height: 70vh;
    }
}

@media (max-width: 768px) {
    body {
        font-size: 0.95rem;
    }
    
    h1 {
        font-size: 2.2rem;
    }
    
    h2 {
        font-size: 1.8rem;
    }
    
    .paper-venue {
        font-size: 0.8rem;
    }
    
    .nav-links {
        position: absolute;
        right: 0;
        height: 92vh;
        top: 8vh;
        background-color: white;
        display: flex;
        flex-direction: column;
        align-items: center;
        width: 50%;
        transform: translateX(100%);
        transition: transform 0.5s ease-in;
        z-index: 1;
        box-shadow: -5px 0 10px rgba(0, 0, 0, 0.1);
    }
    
    .nav-links li {
        opacity: 0;
        margin: 1.5rem 0;
    }
    
    .burger {
        display: block;
    }
    
    .nav-active {
        transform: translateX(0%);
    }
}

@media (max-width: 480px) {
    .section {
        padding: 3rem 0;
    }
    
    .pdf-display-container {
        height: 60vh;
    }
    
    .card, .visualization {
        padding: 1.5rem;
    }
}

/* Navigation Animation */
@keyframes navLinkFade {
    from { opacity: 0; transform: translateX(50px); }
    to { opacity: 1; transform: translateX(0); }
}

.nav-active li {
    animation: navLinkFade 0.5s ease forwards;
}

.teaser-video {
    max-width: 100%;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    transition: var(--transition);
}

.teaser-video:hover {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    transform: translateY(-2px);
}