/* ========================================
   ML4BMI 2025 - Modern Stylesheet
   ======================================== */

/* CSS Variables */
:root {
    --primary-color: #1e3a5f;
    --primary-dark: #152a45;
    --primary-light: #2d5a8a;
    --secondary-color: #4a90d9;
    --accent-color: #f4a261;
    --accent-hover: #e89150;
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-dark: #1a1a2e;
    --text-primary: #2d3748;
    --text-secondary: #4a5568;
    --text-light: #718096;
    --text-white: #ffffff;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.2);
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
    --max-width: 1200px;
    --header-height: 70px;
}

/* Reset & Base */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

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

.container {
    width: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ========================================
   Navigation
   ======================================== */

.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: all var(--transition-base);
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

.nav-logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    letter-spacing: 1px;
    transition: color var(--transition-fast);
}

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

.nav-menu {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-link {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
    padding: 8px 0;
    position: relative;
    transition: color var(--transition-fast);
}

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

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

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

/* Mobile Navigation Toggle */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.hamburger {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--primary-color);
    position: relative;
    transition: background var(--transition-fast);
}

.hamburger::before,
.hamburger::after {
    content: '';
    position: absolute;
    width: 24px;
    height: 2px;
    background: var(--primary-color);
    transition: all var(--transition-fast);
}

.hamburger::before {
    top: -7px;
}

.hamburger::after {
    top: 7px;
}

.nav-toggle.active .hamburger {
    background: transparent;
}

.nav-toggle.active .hamburger::before {
    transform: rotate(45deg);
    top: 0;
}

.nav-toggle.active .hamburger::after {
    transform: rotate(-45deg);
    top: 0;
}

/* ========================================
   Hero Section
   ======================================== */

.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 50%, #0f1f35 100%);
    position: relative;
    padding: calc(var(--header-height) + 40px) 24px 100px;
    text-align: center;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 80%, rgba(74, 144, 217, 0.15) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(244, 162, 97, 0.1) 0%, transparent 50%);
    pointer-events: none;
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 900px;
}

.hero-badge {
    display: inline-block;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--accent-color);
    text-transform: uppercase;
    letter-spacing: 2px;
    padding: 8px 20px;
    border: 2px solid var(--accent-color);
    border-radius: 50px;
    margin-bottom: 24px;
}

.hero-title {
    font-size: 3rem;
    font-weight: 700;
    color: var(--text-white);
    line-height: 1.2;
    margin-bottom: 20px;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

.hero-subtitle {
    font-size: 1.25rem;
    font-weight: 500;
    color: rgba(255, 255, 255, 0.9);
    letter-spacing: 3px;
    text-transform: uppercase;
    margin-bottom: 12px;
}

.hero-location {
    font-size: 1.1rem;
    color: rgba(255, 255, 255, 0.7);
    margin-bottom: 40px;
}

.hero-cta {
    display: inline-block;
    padding: 16px 40px;
    background: var(--accent-color);
    color: var(--text-white);
    font-size: 1rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    border-radius: 50px;
    box-shadow: 0 4px 15px rgba(244, 162, 97, 0.4);
    transition: all var(--transition-base);
}

.hero-cta:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(244, 162, 97, 0.5);
    color: var(--text-white);
}

.hero-scroll {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
}

.scroll-indicator {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.85rem;
    font-weight: 500;
    transition: color var(--transition-base);
}

.scroll-indicator:hover {
    color: var(--text-white);
}

.scroll-indicator svg {
    animation: bounce 2s infinite;
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateY(0);
    }
    40% {
        transform: translateY(10px);
    }
    60% {
        transform: translateY(5px);
    }
}

/* ========================================
   Section Headers
   ======================================== */

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-header h2 {
    font-size: 2.25rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 16px;
}

.section-header.light h2 {
    color: var(--text-white);
}

.section-subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

.section-header.light .section-subtitle {
    color: rgba(255, 255, 255, 0.8);
}

/* ========================================
   About Section
   ======================================== */

.about {
    padding: 100px 0;
    background: var(--bg-primary);
}

.about-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 32px;
    margin-bottom: 60px;
}

.about-card {
    background: var(--bg-secondary);
    padding: 40px 30px;
    border-radius: var(--radius-lg);
    text-align: center;
    transition: all var(--transition-base);
    border: 1px solid var(--border-color);
}

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

.about-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 80px;
    height: 80px;
    background: var(--primary-color);
    color: var(--text-white);
    border-radius: 50%;
    margin-bottom: 24px;
}

.about-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 16px;
}

.about-card p {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.about-full {
    max-width: 900px;
    margin: 0 auto;
    text-align: center;
}

.about-full p {
    font-size: 1.05rem;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 24px;
}

.about-partnership {
    padding-top: 24px;
    border-top: 1px solid var(--border-color);
}

/* ========================================
   Topics Section
   ======================================== */

.topics {
    padding: 100px 0;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    position: relative;
    overflow: hidden;
}

.topics::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 10% 50%, rgba(74, 144, 217, 0.2) 0%, transparent 40%),
        radial-gradient(circle at 90% 50%, rgba(244, 162, 97, 0.15) 0%, transparent 40%);
    pointer-events: none;
}

.topics-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
    position: relative;
    z-index: 1;
}

.topic-item {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    padding: 30px;
    border-radius: var(--radius-lg);
    border: 1px solid rgba(255, 255, 255, 0.2);
    display: flex;
    align-items: flex-start;
    gap: 20px;
    transition: all var(--transition-base);
}

.topic-item:hover {
    background: rgba(255, 255, 255, 0.15);
    transform: translateX(10px);
}

.topic-number {
    font-size: 2rem;
    font-weight: 700;
    color: var(--accent-color);
    line-height: 1;
    min-width: 50px;
}

.topic-item h3 {
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--text-white);
    line-height: 1.5;
}

/* ========================================
   Dates Section
   ======================================== */

.dates {
    padding: 100px 0;
    background: var(--bg-primary);
}

.dates-timeline {
    display: flex;
    flex-direction: column;
    gap: 0;
    max-width: 700px;
    margin: 0 auto;
    position: relative;
}

.dates-timeline::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--border-color);
}

.date-item {
    display: flex;
    align-items: flex-start;
    gap: 30px;
    padding: 30px 0;
    position: relative;
}

.date-item:not(:last-child) {
    border-bottom: 1px solid var(--border-color);
}

.date-marker {
    width: 42px;
    height: 42px;
    background: var(--bg-secondary);
    border: 3px solid var(--secondary-color);
    border-radius: 50%;
    flex-shrink: 0;
    position: relative;
    z-index: 1;
}

.date-item.highlight .date-marker {
    background: var(--accent-color);
    border-color: var(--accent-color);
}

.date-content {
    display: flex;
    flex-direction: column;
    gap: 8px;
    flex: 1;
}

.date-label {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-light);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.date-value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.date-location {
    font-size: 1rem;
    color: var(--text-secondary);
}

.date-item.highlight .date-value {
    color: var(--accent-color);
}

/* ========================================
   Committee Section
   ======================================== */

.committee {
    padding: 100px 0;
    background: var(--bg-secondary);
}

.committee-section {
    margin-bottom: 60px;
}

.committee-section:last-child {
    margin-bottom: 0;
}

.committee-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
    text-align: center;
    margin-bottom: 40px;
}

.chairs-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
    margin-bottom: 40px;
}

.chair-card {
    background: var(--bg-primary);
    padding: 40px 30px;
    border-radius: var(--radius-lg);
    text-align: center;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    transition: all var(--transition-base);
}

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

.chair-avatar {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: var(--text-white);
    font-size: 1.75rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    margin: 0 auto 20px;
}

.chair-info h4 {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 4px;
}

.chair-info p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 4px;
}

.chair-affiliation {
    font-size: 0.85rem;
    color: var(--text-light);
    margin-bottom: 12px;
}

.chair-email {
    font-size: 0.85rem;
    color: var(--secondary-color);
    word-break: break-all;
}

.chair-email:hover {
    color: var(--primary-color);
}

.members-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.member-item {
    background: var(--bg-primary);
    padding: 24px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
    transition: all var(--transition-base);
}

.member-item:hover {
    border-color: var(--secondary-color);
    box-shadow: var(--shadow-md);
}

.member-name {
    display: block;
    font-size: 1rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 6px;
}

.member-affiliation {
    display: block;
    font-size: 0.85rem;
    color: var(--text-light);
}

/* ========================================
   Submit Section
   ======================================== */

.submit {
    padding: 100px 0;
    background: linear-gradient(135deg, var(--primary-dark) 0%, var(--primary-color) 100%);
    text-align: center;
}

.submit-content {
    max-width: 600px;
    margin: 0 auto;
}

.submit h2 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-white);
    margin-bottom: 20px;
}

.submit p {
    font-size: 1.1rem;
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: 40px;
    line-height: 1.7;
}

.submit-btn {
    display: inline-block;
    padding: 18px 50px;
    background: var(--accent-color);
    color: var(--text-white);
    font-size: 1.1rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    border-radius: 50px;
    box-shadow: 0 4px 20px rgba(244, 162, 97, 0.4);
    transition: all var(--transition-base);
}

.submit-btn:hover {
    background: var(--accent-hover);
    transform: translateY(-3px);
    box-shadow: 0 8px 30px rgba(244, 162, 97, 0.5);
    color: var(--text-white);
}

.submit-note {
    margin-top: 24px;
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.5);
}

/* ========================================
   Footer
   ======================================== */

.footer {
    padding: 60px 0 30px;
    background: var(--bg-dark);
    color: var(--text-white);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 40px;
    padding-bottom: 40px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-brand h3 {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: 10px;
    letter-spacing: 1px;
}

.footer-brand p {
    font-size: 0.95rem;
    color: rgba(255, 255, 255, 0.6);
    max-width: 300px;
}

.footer-links {
    display: flex;
    flex-wrap: wrap;
    gap: 24px;
}

.footer-links a {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.7);
    transition: color var(--transition-fast);
}

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

.footer-bottom {
    text-align: center;
}

.footer-bottom p {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.5);
    margin-bottom: 8px;
}

.footer-tagline {
    font-size: 0.85rem;
    color: rgba(255, 255, 255, 0.4);
}

/* ========================================
   Responsive Design
   ======================================== */

@media (max-width: 1024px) {
    .about-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .chairs-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .members-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 768px) {
    /* Navigation */
    .nav-toggle {
        display: block;
    }
    
    .nav-menu {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        background: var(--bg-primary);
        flex-direction: column;
        align-items: center;
        padding: 20px;
        gap: 0;
        box-shadow: var(--shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
    }
    
    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .nav-link {
        display: block;
        padding: 16px;
        width: 100%;
        text-align: center;
        border-bottom: 1px solid var(--border-color);
    }
    
    .nav-link:last-child {
        border-bottom: none;
    }
    
    /* Hero */
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    /* About */
    .about-grid {
        grid-template-columns: 1fr;
    }
    
    /* Topics */
    .topics-grid {
        grid-template-columns: 1fr;
    }
    
    /* Committee */
    .chairs-grid {
        grid-template-columns: 1fr;
    }
    
    .members-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    /* Footer */
    .footer-content {
        flex-direction: column;
        gap: 30px;
        text-align: center;
    }
    
    .footer-brand p {
        max-width: none;
    }
    
    .footer-links {
        justify-content: center;
    }
}

@media (max-width: 480px) {
    :root {
        --header-height: 60px;
    }
    
    .hero-title {
        font-size: 1.75rem;
    }
    
    .section-header h2 {
        font-size: 1.75rem;
    }
    
    .members-grid {
        grid-template-columns: 1fr;
    }
    
    .topic-item {
        flex-direction: column;
        text-align: center;
    }
    
    .chairs-grid,
    .about-grid,
    .topics-grid {
        gap: 16px;
    }
}

/* ========================================
   Print Styles
   ======================================== */

@media print {
    .navbar,
    .hero-scroll,
    .submit-btn,
    .hero-cta {
        display: none;
    }
    
    .hero {
        min-height: auto;
        padding: 40px 24px;
    }
    
    body {
        font-size: 12pt;
        line-height: 1.5;
    }
    
    .about-card,
    .chair-card,
    .member-item,
    .topic-item {
        break-inside: avoid;
    }
}