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

:root {
    /* Color System */
    --primary-50: #eff6ff;
    --primary-100: #dbeafe;
    --primary-200: #bfdbfe;
    --primary-300: #93c5fd;
    --primary-400: #60a5fa;
    --primary-500: #3b82f6;
    --primary-600: #2563eb;
    --primary-700: #1d4ed8;
    --primary-800: #1e40af;
    --primary-900: #1e3a8a;
    --primary-950: #172554;

    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --gray-950: #030712;

    --accent-500: #f59e0b;
    --accent-600: #d97706;
    
    --success-500: #10b981;
    --warning-500: #f59e0b;
    --error-500: #ef4444;

    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-serif: 'Crimson Text', Georgia, serif;

    /* Spacing */
    --space-1: 0.25rem;
    --space-2: 0.5rem;
    --space-3: 0.75rem;
    --space-4: 1rem;
    --space-5: 1.25rem;
    --space-6: 1.5rem;
    --space-8: 2rem;
    --space-10: 2.5rem;
    --space-12: 3rem;
    --space-16: 4rem;
    --space-20: 5rem;
    --space-24: 6rem;

    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

    /* Border Radius */
    --radius-sm: 0.125rem;
    --radius: 0.25rem;
    --radius-md: 0.375rem;
    --radius-lg: 0.5rem;
    --radius-xl: 0.75rem;
    --radius-2xl: 1rem;
    --radius-3xl: 1.5rem;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: var(--font-sans);
    line-height: 1.6;
    color: var(--gray-800);
    background-color: white;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-6);
}

@media (max-width: 768px) {
    .container {
        padding: 0 var(--space-4);
    }
}

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--gray-200);
    z-index: 1000;
    transition: all var(--transition-normal);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--space-6);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 4rem;
}

.nav-brand {
    font-weight: 600;
    font-size: 1.125rem;
    color: var(--primary-700);
}

.brand-text {
    transition: color var(--transition-fast);
}

.brand-text:hover {
    color: var(--primary-600);
}

.nav-menu {
    display: flex;
    gap: var(--space-8);
    align-items: center;
}

.nav-link {
    text-decoration: none;
    color: var(--gray-700);
    font-weight: 500;
    transition: color var(--transition-fast);
    position: relative;
}

.nav-link:hover {
    color: var(--primary-600);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -0.5rem;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-600);
    transition: width var(--transition-normal);
}

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

.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: var(--space-1);
}

.bar {
    width: 25px;
    height: 2px;
    background-color: var(--gray-700);
    transition: all var(--transition-fast);
}

@media (max-width: 768px) {
    .nav-container {
        padding: 0 var(--space-4);
    }
    
    .nav-menu {
        position: fixed;
        top: 4rem;
        left: -100%;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: var(--space-8);
        box-shadow: var(--shadow-lg);
        transition: left var(--transition-normal);
        border-top: 1px solid var(--gray-200);
    }

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

    .nav-toggle {
        display: flex;
    }

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

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

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

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-50) 0%, var(--gray-50) 100%);
    padding: var(--space-24) 0 var(--space-16);
    margin-top: 4rem;
    text-align: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.conference-badge {
    margin-bottom: var(--space-6);
}

.badge {
    display: inline-block;
    background: var(--primary-600);
    color: white;
    padding: var(--space-2) var(--space-4);
    border-radius: var(--radius-lg);
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    animation: fadeInUp 0.6s ease-out;
}

.hero-title {
    font-family: var(--font-serif);
    font-size: 3rem;
    font-weight: 600;
    line-height: 1.2;
    color: var(--gray-900);
    margin-bottom: var(--space-6);
    animation: fadeInUp 0.6s ease-out 0.2s both;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--gray-600);
    margin-bottom: var(--space-10);
    animation: fadeInUp 0.6s ease-out 0.4s both;
}

.hero-actions {
    display: flex;
    gap: var(--space-4);
    justify-content: center;
    flex-wrap: wrap;
    animation: fadeInUp 0.6s ease-out 0.6s both;
}

@media (max-width: 768px) {
    .hero {
        padding: var(--space-16) 0 var(--space-12);
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .hero-actions {
        flex-direction: column;
        align-items: center;
    }
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-6);
    border-radius: var(--radius-lg);
    font-weight: 500;
    text-decoration: none;
    transition: all var(--transition-normal);
    cursor: pointer;
    border: none;
    font-size: 1rem;
    position: relative;
    overflow: hidden;
}

.btn-icon {
    width: 1.25rem;
    height: 1.25rem;
}

.btn-primary {
    background: var(--primary-600);
    color: white;
    box-shadow: var(--shadow);
}

.btn-primary:hover {
    background: var(--primary-700);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-secondary {
    background: white;
    color: var(--primary-600);
    border: 2px solid var(--primary-600);
}

.btn-secondary:hover {
    background: var(--primary-600);
    color: white;
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-outline {
    background: transparent;
    color: var(--gray-700);
    border: 2px solid var(--gray-300);
}

.btn-outline:hover {
    background: var(--gray-100);
    border-color: var(--gray-400);
    transform: translateY(-2px);
}

/* Sections */
.section {
    padding: var(--space-16) 0;
}

.section-gray {
    background-color: var(--gray-50);
}

.section-header {
    text-align: center;
    margin-bottom: var(--space-12);
}

.section-title {
    font-family: var(--font-serif);
    font-size: 2.5rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: var(--space-4);
}

.section-description {
    font-size: 1.125rem;
    color: var(--gray-600);
    max-width: 600px;
    margin: 0 auto;
}

@media (max-width: 768px) {
    .section {
        padding: var(--space-12) 0;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    .section-description {
        font-size: 1rem;
    }
}

/* Authors Section */
.authors-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-8);
    max-width: 800px;
    margin: 0 auto;
}

.author-card {
    background: white;
    padding: var(--space-8);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow);
    text-align: center;
    transition: all var(--transition-normal);
}

.author-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.author-name {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: var(--space-2);
}

.author-affiliation {
    color: var(--gray-600);
    margin-bottom: var(--space-1);
}

.author-email {
    color: var(--primary-600);
    font-size: 0.875rem;
}

/* Abstract Section */
.abstract-content {
    max-width: 800px;
    margin: 0 auto;
}

.abstract-text {
    background: white;
    padding: var(--space-10);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow);
    font-size: 1.125rem;
    line-height: 1.7;
}

.abstract-text p {
    margin-bottom: var(--space-6);
}

.abstract-text p:last-child {
    margin-bottom: 0;
}

/* Paper Viewer Section */
.paper-viewer {
    max-width: 900px;
    margin: 0 auto;
}

.pdf-container {
    background: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
    margin-bottom: var(--space-8);
}

.pdf-viewer {
    width: 100%;
    height: 800px;
    border: none;
    display: block;
}

.paper-actions {
    display: flex;
    gap: var(--space-4);
    justify-content: center;
    flex-wrap: wrap;
}

@media (max-width: 768px) {
    .pdf-viewer {
        height: 600px;
    }
    
    .paper-actions {
        flex-direction: column;
        align-items: center;
    }
}

/* Citation Section */
.citation-container {
    max-width: 800px;
    margin: 0 auto;
    background: white;
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.citation-tabs {
    display: flex;
    border-bottom: 1px solid var(--gray-200);
}

.citation-tab {
    flex: 1;
    padding: var(--space-4) var(--space-6);
    background: none;
    border: none;
    cursor: pointer;
    font-weight: 500;
    color: var(--gray-600);
    transition: all var(--transition-fast);
    position: relative;
}

.citation-tab.active {
    color: var(--primary-600);
    background: var(--primary-50);
}

.citation-tab:hover {
    background: var(--gray-50);
}

.citation-tab.active:hover {
    background: var(--primary-50);
}

.citation-content {
    position: relative;
    padding: var(--space-8);
}

.citation-format {
    display: none;
}

.citation-format.active {
    display: block;
}

.citation-text {
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 0.875rem;
    line-height: 1.6;
    color: var(--gray-800);
    background: var(--gray-50);
    padding: var(--space-6);
    border-radius: var(--radius-lg);
    margin: 0;
    overflow-x: auto;
}

.copy-citation {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    margin-top: var(--space-6);
    padding: var(--space-3) var(--space-4);
    background: var(--primary-600);
    color: white;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    font-weight: 500;
    transition: all var(--transition-fast);
}

.copy-citation:hover {
    background: var(--primary-700);
    transform: translateY(-1px);
}

.copy-icon {
    width: 1rem;
    height: 1rem;
}

/* Contributions Section */
.contributions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--space-8);
}

.contribution-card {
    background: white;
    padding: var(--space-8);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow);
    text-align: center;
    transition: all var(--transition-normal);
    border: 1px solid var(--gray-100);
}

.contribution-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-200);
}

.contribution-icon {
    width: 3rem;
    height: 3rem;
    background: var(--primary-100);
    border-radius: var(--radius-xl);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto var(--space-6);
    color: var(--primary-600);
    transition: all var(--transition-normal);
}

.contribution-card:hover .contribution-icon {
    background: var(--primary-600);
    color: white;
    transform: scale(1.1);
}

.contribution-icon svg {
    width: 1.5rem;
    height: 1.5rem;
}

.contribution-title {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: var(--space-4);
}

.contribution-description {
    color: var(--gray-600);
    line-height: 1.6;
}

/* Footer */
.footer {
    background: var(--gray-900);
    color: var(--gray-300);
    padding: var(--space-16) 0 var(--space-8);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-10);
    margin-bottom: var(--space-10);
}

.footer-title {
    color: white;
    font-weight: 600;
    margin-bottom: var(--space-4);
}

.footer-text {
    line-height: 1.6;
    color: var(--gray-400);
}

.footer-links {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.footer-link {
    color: var(--gray-400);
    text-decoration: none;
    transition: color var(--transition-fast);
}

.footer-link:hover {
    color: var(--primary-400);
}

.footer-bottom {
    border-top: 1px solid var(--gray-700);
    padding-top: var(--space-8);
    text-align: center;
}

.footer-copyright {
    color: var(--gray-400);
    font-size: 0.875rem;
}

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

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

/* Scroll Behavior */
html {
    scroll-behavior: smooth;
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
    
    html {
        scroll-behavior: auto;
    }
}

/* Focus States */
.btn:focus,
.nav-link:focus,
.citation-tab:focus,
.copy-citation:focus {
    outline: 2px solid var(--primary-600);
    outline-offset: 2px;
}

/* Print Styles */
@media print {
    .navbar,
    .hero-actions,
    .paper-actions,
    .copy-citation,
    .footer {
        display: none;
    }
    
    .hero {
        margin-top: 0;
        padding: var(--space-8) 0;
    }
    
    .section {
        padding: var(--space-8) 0;
    }
    
    body {
        font-size: 12pt;
        line-height: 1.4;
    }
}

.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.resource-card {
    background-color: #fff;
    border: 1px solid #ddd;
    padding: 1.2rem;
    border-radius: 8px;
    box-shadow: 0 2px 6px rgba(0,0,0,0.05);
    transition: transform 0.2s ease;
}

.resource-card:hover {
    transform: translateY(-4px);
}

.resource-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: #333;
}

.resource-link {
    font-size: 0.95rem;
    color: #0056d2;
    text-decoration: none;
}

.resource-link:hover {
    text-decoration: underline;
}