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

:root {
    --primary-color: #7c3aed; /* Purple-600 - kept for logo/accents */
    --secondary-color: #5b21b6; /* Purple-800 */
    --accent-color: #8b5cf6; /* Purple-500 */
    --dark-color: #1a1a1a; /* Changed to dark gray/black for text */
    --light-color: #ffffff;
    --gray-color: #4a4a4a;
    --light-gray: #f8fafc;
    --success-color: #059669;
    --warning-color: #d97706;
    --danger-color: #dc2626;
    --border-radius: 12px;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    --gradient: linear-gradient(135deg, #4c1d95 0%, #8b5cf6 100%); /* Kept for reference if needed, but hero uses white */
}

html, body {
    height: 100%;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.7;
    color: var(--dark-color);
    background-color: var(--light-color);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

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

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.08);
    z-index: 1000;
    padding: 20px 0;
    box-shadow: var(--shadow);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-size: 24px;
    font-weight: 700;
    color: var(--primary-color); /* Logo remains purple */
}

.nav-logo img {
    border-radius: 6px;
}

.nav-links {
    display: flex;
    gap: 30px;
}

.nav-links a {
    text-decoration: none;
    color: var(--dark-color);
    font-weight: 500;
    position: relative;
}

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

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

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

/* Hero Section */
.hero {
    padding: 140px 0 100px;
    background: white; /* Changed to white */
    color: var(--dark-color); /* Changed to dark text */
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
}

/* Removed hero::before overlay */

.hero-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
    display: grid;
    grid-template-columns: 1fr;
    gap: 40px;
    align-items: center;
    text-align: center; 
}

.hero-content {
    padding-right: 0;
    max-width: 1000px;
    margin: 0 auto;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: #f3f4f6; /* Light gray bg */
    color: var(--dark-color); /* Dark text */
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 14px;
    font-weight: 500;
    margin-bottom: 20px;
    backdrop-filter: blur(10px);
    border: 1px solid #e5e7eb;
}

.hero-title {
    font-size: 2.8rem;
    font-weight: 800;
    margin-bottom: 24px;
    line-height: 1.1;
    color: var(--dark-color); /* Black text */
    letter-spacing: -0.02em;
    text-shadow: none;
}

.math-symbol {
    color: var(--dark-color); /* Black text */
    font-weight: 900;
    text-shadow: none;
}

.hero-authors {
    margin-bottom: 30px;
    font-size: 1.1rem;
    line-height: 1.6;
    color: var(--dark-color);
}

.hero-authors a {
    color: hsl(204, 86%, 53%); /* H-RDT blue */
    text-decoration: none;
}

.hero-authors a:hover {
    text-decoration: underline;
}

.hero-authors sup {
    margin-left: 2px;
}

.hero-affiliations {
    margin-bottom: 30px;
    font-size: 1.1rem;
    color: var(--dark-color);
    line-height: 1.6;
}

.hero-description {
    font-size: 1.1rem;
    margin-bottom: 30px;
    color: var(--gray-color);
    line-height: 1.7;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.hero-buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
    margin-bottom: 40px;
    flex-wrap: wrap;
    align-items: center;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 12px 28px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 600;
    cursor: pointer;
    border: none;
    font-size: 16px;
    box-shadow: var(--shadow);
    position: relative;
    overflow: hidden;
    transition: all 0.3s ease;
}

.btn-primary {
    background: var(--dark-color); /* Black button */
    color: white;
}

.btn-primary:hover {
    background: #333;
    box-shadow: var(--shadow-xl);
    transform: translateY(-2px);
}

.btn-secondary {
    background: white;
    color: var(--dark-color);
    border: 1px solid #e5e7eb;
}

.btn-secondary:hover {
    background: #f9fafb;
    transform: translateY(-2px);
}

/* H-RDT style buttons */
.external-link.button {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    border: none;
    font-size: 16px;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.external-link.button.is-dark {
    background-color: #363636;
    color: #fff;
}

.external-link.button.is-dark:hover {
    background-color: #2a2a2a;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
}

.external-link.button.is-normal {
    font-size: 1rem;
}

.external-link.button.is-rounded {
    border-radius: 50px;
}

.external-link.button .icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.external-link.button .icon i {
    font-size: 1em;
}

.hero-visual {
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    margin-top: 20px;
}

.visual-container {
    width: 100%;
    max-width: 1000px;
}

.research-highlights {
    width: 100%;
    margin-top: 20px;
}

.highlights-title {
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--dark-color); /* Dark title */
    margin-bottom: 24px;
    text-align: center;
    position: relative;
}

.highlights-title::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 40px;
    height: 2px;
    background: var(--primary-color);
    border-radius: 1px;
}

.highlight-list {
    display: flex;
    flex-direction: row; /* Horizontal layout */
    gap: 20px;
    justify-content: center;
    flex-wrap: wrap;
}

.highlight-item {
    display: flex;
    align-items: flex-start;
    gap: 16px;
    padding: 20px;
    background: #ffffff; /* White bg */
    border-radius: var(--border-radius);
    border: 1px solid #e5e7eb; /* Light border */
    flex: 1;
    min-width: 280px;
    box-shadow: var(--shadow);
}

.highlight-item:hover {
    box-shadow: var(--shadow-lg);
    border-color: var(--accent-color);
}

.highlight-icon {
    flex-shrink: 0;
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    color: white;
    box-shadow: 0 4px 12px rgba(124, 58, 237, 0.3);
}

.highlight-content h4 {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--dark-color); /* Dark text */
    margin: 0 0 6px 0;
    line-height: 1.3;
    text-align: left;
}

.highlight-content p {
    font-size: 0.9rem;
    color: var(--gray-color); /* Gray text */
    margin: 0;
    line-height: 1.4;
    text-align: left;
}

.demo-video {
    position: relative;
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    background: #000;
}

.demo-video video {
    width: 100%;
    height: auto;
    display: block;
}

/* Section Styles */
section {
    padding: 100px 0;
    position: relative;
    z-index: 1;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 60px;
    color: var(--dark-color);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 15px;
}

/* section-icon removed from layout but kept style just in case */
.section-icon {
    font-size: 1.6rem;
    color: white;
    background: var(--primary-color);
    padding: 8px;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

/* For performance section, use purple gradient */
.performance .section-icon {
    background: var(--gradient);
}

/* Framework Section */
.framework {
    background: white;
    padding: 80px 0 100px;
}

.subsection-title {
    font-size: 1.6rem;
    font-weight: 600;
    text-align: left;
    margin-bottom: 30px;
    margin-left: 0;
    color: var(--dark-color);
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    padding: 15px 25px;
    border-radius: 12px;
    border-left: 4px solid var(--primary-color);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
    display: inline-block;
    width: auto;
}

.paradigm-section, .architecture-section {
    margin-bottom: 80px;
}

.paradigm-figure, .architecture-figure {
    text-align: center;
    margin-bottom: 30px;
}

.paradigm-image, .architecture-image {
    max-width: 90%;
    height: auto;
    border-radius: var(--border-radius);
    margin-bottom: 20px;
    box-shadow: var(--shadow);
}

.figure-caption {
    font-size: 1rem;
    color: var(--gray-color);
    line-height: 1.6;
    text-align: center; /* Centered for single column figures */
    max-width: 900px;
    margin: 0 auto;
}

/* Performance Section */
.performance {
    background: #f8fafc;
}

.performance-grid {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.performance-card {
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    max-width: 95%;
    margin: 0 auto;
}

.performance-card h3 {
    background: var(--gradient);
    color: white;
    margin: 0;
    padding: 24px 20px;
    font-size: 1.2rem;
    font-weight: 700;
    letter-spacing: 0.5px;
}

.performance-table {
    overflow-x: auto;
    width: 100%;
    margin: 0 auto;
}

.performance table {
    width: 100%;
    border-collapse: collapse;
    background: white;
    margin: 0 auto;
    font-size: 0.95rem;
    table-layout: auto;
}

.performance table th:first-child,
.performance table td:first-child {
    min-width: 200px;
    white-space: normal;
    word-wrap: break-word;
}

.performance th,
.performance td {
    padding: 12px 16px;
    text-align: left;
    border-bottom: 1px solid #e5e7eb;
}

.performance th {
    background: #f8fafc;
    font-weight: 600;
    color: var(--dark-color);
    font-size: 14px;
}

.performance tr:last-child td {
    border-bottom: none;
}

.performance .improvement {
    color: var(--success-color);
    font-weight: 600;
}

/* Demo Section */
.demo {
    background: #f8fafc;
}

.demo-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 20px;
}

.demo-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 35px;
}

.demo-card {
    background: white;
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

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

.demo-info {
    padding: 20px;
}

.demo-info h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--dark-color);
}

.demo-info p {
    color: var(--gray-color);
    margin-bottom: 15px;
    font-size: 14px;
}

.performance-badge {
    display: inline-block;
    background: linear-gradient(135deg, var(--success-color), #34d399);
    color: white;
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 12px;
    font-weight: 600;
}

/* Citation Section */
.citation {
    background: white;
}

.citation-content {
    max-width: 1000px;
    margin: 0 auto;
}

.citation-text {
    background: #f8fafc;
    padding: 30px;
    border-radius: var(--border-radius);
    border-left: 4px solid var(--primary-color);
    overflow-x: auto;
}

.citation-text pre {
    margin: 0;
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 14px;
    line-height: 1.5;
    color: var(--dark-color);
}

/* Footer */
.footer {
    background: var(--dark-color);
    color: white;
    padding: 60px 0 30px;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    margin-bottom: 40px;
    flex-wrap: wrap;
    gap: 40px;
}

.footer-info p {
    color: #9ca3af;
    font-size: 1.1rem;
    line-height: 1.4;
}

.footer-section h4 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 15px;
    color: white;
}

.footer-section a {
    display: block;
    color: #9ca3af;
    text-decoration: none;
    margin-bottom: 8px;
}

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

.footer-bottom {
    border-top: 1px solid #374151;
    padding-top: 30px;
    text-align: center;
    color: #9ca3af;
}

/* Experts Grid in Framework */
.experts-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 25px;
    max-width: 1200px;
    margin: 0 auto;
}

/* Responsive */
@media (max-width: 768px) {
    .hero-title {
        font-size: 2.5rem;
    }
    
    .nav-links {
        display: none; /* Simplification for mobile */
    }
    
    .demo-grid, .experts-grid, .highlight-list {
        grid-template-columns: 1fr;
        flex-direction: column;
    }
}