/* ==========================================
   Disabled/Coming Soon Button
   ========================================== */
.btn-disabled {
    background-color: #e5e7eb;
    color: #9ca3af;
    border: 2px solid #e5e7eb;
    cursor: not-allowed;
    pointer-events: none;
    opacity: 1;
    font-weight: 500;
    transition: none;
    box-shadow: none;
}
/* ==========================================
   Program Committee Section
   ========================================== */
.pc-list {
    list-style: none;
    padding-left: 0;
    margin: var(--spacing-md) 0;
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}
.pc-list li {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-xs) 0;
    border-bottom: 1px solid var(--color-border);
    font-size: var(--font-size-large);
}
.pc-list li:last-child {
    border-bottom: none;
}
.pc-name {
    font-weight: 500;
    color: var(--color-text);
}
.pc-affiliation {
    color: var(--color-text-muted);
    font-size: var(--font-size-small);
    font-weight: 400;
}
/* ==========================================
   CSS Variables
   ========================================== */
:root {
    /* Colors - Modern Fresh Theme */
    --color-primary: #14b8a6;
    --color-primary-dark: #0f766e;
    --color-primary-light: #5eead4;
    --color-accent: #8b5cf6;
    --color-accent-dark: #7c3aed;
    --color-secondary: #334155;
    --color-text: #0f172a;
    --color-text-light: #64748b;
    --color-text-muted: #94a3b8;
    --color-background: #ffffff;
    --color-background-gray: #f8fafc;
    --color-background-dark: #1e293b;
    --color-border: #e2e8f0;
    --color-shadow: rgba(0, 0, 0, 0.08);
    --color-shadow-lg: rgba(0, 0, 0, 0.15);
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    --font-size-base: 16px;
    --font-size-small: 0.875rem;
    --font-size-large: 1.125rem;
    --line-height-base: 1.6;
    --line-height-heading: 1.2;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 3rem;
    --spacing-xl: 4rem;
    
    /* Layout */
    --container-max-width: 960px;
    --nav-height: 70px;
    
    /* Transitions */
    --transition-speed: 0.3s;
    --transition-speed: 0.3s;
}

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

html {
    scroll-behavior: smooth;
    font-size: var(--font-size-base);
}

body {
    font-family: var(--font-family);
    line-height: var(--line-height-base);
    color: var(--color-text);
    background-color: var(--color-background);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ==========================================
   Typography
   ========================================== */
h1, h2, h3, h4, h5, h6 {
    line-height: var(--line-height-heading);
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
    color: var(--color-text);
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
}

h2 {
    font-size: 2rem;
}

h3 {
    font-size: 1.5rem;
}

p {
    margin-bottom: var(--spacing-sm);
}

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

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

a:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* ==========================================
   Layout Components
   ========================================== */
.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.section {
    padding: var(--spacing-xl) 0;
    border-bottom: 1px solid var(--color-border);
}

.section:last-of-type {
    border-bottom: none;
}


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

.section-title {
    text-align: center;
    margin-bottom: var(--spacing-lg);
    color: var(--color-text);
}

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

/* ==========================================
   Header & Navigation
   ========================================== */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background-color: var(--color-background);
    border-bottom: 1px solid var(--color-border);
    z-index: 1000;
    box-shadow: 0 2px 4px var(--color-shadow);
}

.nav {
    height: var(--nav-height);
}

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

.nav-brand a {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-right: 2.5rem; /* Add space between brand and menu */
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: var(--spacing-md);
    align-items: center;
}

.nav-link {
    color: var(--color-secondary);
    font-weight: 500;
    padding: var(--spacing-xs) 0;
    position: relative;
    transition: color var(--transition-speed);
}

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--color-primary);
}

/* Hamburger Menu */
.nav-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
    z-index: 1001;
}

.hamburger {
    width: 25px;
    height: 2px;
    background-color: var(--color-text);
    margin: 3px 0;
    transition: all var(--transition-speed);
}

/* ==========================================
   Hero Section
   ========================================== */
.hero {
    position: relative;
    padding: calc(var(--nav-height) + var(--spacing-xl)) 0 var(--spacing-xl);
    text-align: center;
    min-height: 80vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: url('../img/hero-background.jpg');
    background-size: cover;
    background-position: center;
    background-repeat: no-repeat;
    z-index: 0;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(120deg, rgba(20,184,166,0.35) 0%, rgba(139,92,246,0.35) 100%);
    backdrop-filter: blur(2px);
    z-index: 1;
}

.hero .container {
    position: relative;
    z-index: 2;
}

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

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-md);
    color: var(--color-background);
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.hero-subtitle {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--color-background);
    margin-bottom: var(--spacing-sm);
    text-shadow: 2px 2px 8px rgba(0,0,0,0.7), 0 0 20px rgba(0,0,0,0.4);
}

.hero-conference {
    font-size: var(--font-size-large);
    font-weight: 700;
    color: var(--color-background);
    margin-bottom: var(--spacing-lg);
    text-shadow: 2px 2px 12px rgba(0,0,0,0.8), 0 0 24px rgba(0,0,0,0.5);
    letter-spacing: 0.5px;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
    flex-wrap: wrap;
}

/* ==========================================
   Buttons
   ========================================== */
.btn {
    display: inline-block;
    padding: 0.75rem 2rem;
    font-size: 1rem;
    font-weight: 500;
    text-align: center;
    border-radius: 6px;
    transition: all var(--transition-speed);
    cursor: pointer;
    border: 2px solid transparent;
}

.btn-primary {
    background-color: var(--color-accent);
    color: var(--color-background);
    border-color: var(--color-accent);
}

.btn-primary:hover {
    background-color: var(--color-accent-dark);
    color: var(--color-background);
    transform: translateY(-2px);
    box-shadow: 0 6px 12px var(--color-shadow-lg);
}

.btn-secondary {
    background-color: var(--color-background);
    color: var(--color-primary);
    border-color: var(--color-background);
}

.btn-secondary:hover {
    background-color: var(--color-background);
    color: var(--color-primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 6px 12px var(--color-shadow-lg);
}

/* ==========================================
   Topics Grid
   ========================================== */
.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: calc(var(--spacing-lg) * 0.8) var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.topic-card {
    background-color: var(--color-background);
    padding: var(--spacing-lg) var(--spacing-md) var(--spacing-md) var(--spacing-md);
    border-radius: 10px;
    border: 1px solid var(--color-border);
    transition: box-shadow var(--transition-speed);
    position: relative;
    box-shadow: 0 2px 8px var(--color-shadow);
    margin-bottom: var(--spacing-md);
}

.topic-card::before {
    content: '';
    position: absolute;
    left: 0;
    top: 1.2rem;
    bottom: 1.2rem;
    width: 5px;
    border-radius: 4px;
    background: linear-gradient(180deg, var(--color-primary) 60%, var(--color-accent) 100%);
    opacity: 0.7;
}
}

.topic-card:hover {
    box-shadow: 0 4px 12px var(--color-shadow);
}

.topic-card h3 {
    color: var(--color-primary);
    margin-bottom: var(--spacing-sm);
    font-size: 1.25rem;
    font-weight: 700;
    letter-spacing: 0.01em;
    padding-left: 0.5rem;
}

.topic-card ul {
    list-style: none;
    padding-left: 0;
}

.topic-card li {
    padding: 0.25rem 0;
    padding-left: 1.25rem;
    position: relative;
}

.topic-card li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--color-primary);
    font-weight: 600;
}

/* ==========================================
   Schedule Table
   ========================================== */
.program-note {
    text-align: center;
    font-style: italic;
    color: var(--color-text-light);
    margin-bottom: var(--spacing-md);
}

.schedule-wrapper {
    overflow-x: auto;
    margin-top: var(--spacing-md);
}

.schedule-table {
    width: 100%;
    border-collapse: collapse;
    background-color: var(--color-background);
    border: 1px solid var(--color-border);
    border-radius: 8px;
    overflow: hidden;
}

.schedule-table thead {
    background-color: var(--color-primary);
    color: var(--color-background);
}

.schedule-table th,
.schedule-table td {
    padding: var(--spacing-sm);
    text-align: left;
    border-bottom: 1px solid var(--color-border);
}

.schedule-table th {
    font-weight: 600;
}

.schedule-table tbody tr:hover {
    background-color: var(--color-background-gray);
}

.schedule-table tbody tr:last-child td {
    border-bottom: none;
}

/* ==========================================
   Speakers & Organizers
   ========================================== */
.speakers-grid {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.organizers-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.organizer-card {
    text-align: center;
    padding: var(--spacing-sm);
}

.organizer-link {
    display: block;
    text-decoration: none;
    color: inherit;
    transition: all var(--transition-speed);
}

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

.organizer-photo {
    width: 150px;
    height: 150px;
    object-fit: cover;
    border-radius: 50%;
    margin: 0 auto var(--spacing-sm);
    display: block;
    border: 3px solid var(--color-border);
    transition: all var(--transition-speed);
}

.organizer-link:hover .organizer-photo {
    border-color: var(--color-primary);
    transform: scale(1.05);
    box-shadow: 0 4px 12px var(--color-shadow-lg);
}

.organizer-card h3 {
    color: var(--color-text);
    margin-bottom: var(--spacing-xs);
    font-size: 1.1rem;
}

.speaker-card,
.organizer-card {
    background-color: var(--color-background);
    padding: var(--spacing-md);
    border-radius: 8px;
    border: 1px solid var(--color-border);
    transition: transform var(--transition-speed), box-shadow var(--transition-speed);
}

.speaker-card {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-md);
}

.speaker-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px var(--color-shadow-lg);
}

.organizer-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 20px var(--color-shadow-lg);
}

.speaker-photo {
    width: 180px;
    height: 180px;
    min-width: 180px;
    object-fit: cover;
    border-radius: 8px;
}

.speaker-card h3 {
    color: var(--color-text);
    margin-bottom: var(--spacing-xs);
}

.speaker-info {
    flex: 1;
}

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

.speaker-card h3 a:hover {
    color: var(--color-accent);
    text-decoration: underline;
}

.speaker-affiliation {
    color: var(--color-text-muted);
    font-weight: 500;
    font-size: var(--font-size-small);
    margin-bottom: var(--spacing-sm);
}

.organizer-affiliation {
    color: var(--color-text-muted);
    font-weight: 400;
    font-size: var(--font-size-small);
    margin-bottom: 0;
}

.speaker-bio,
.organizer-bio {
    color: var(--color-text-light);
    font-size: var(--font-size-small);
    line-height: 1.5;
}

.speakers-note {
    text-align: center;
    margin-top: var(--spacing-md);
    font-style: italic;
    color: var(--color-text-light);
}

/* ==========================================
   Call for Papers
   ========================================== */
.cfp-list,
.challenge-list,
.dates-list {
    list-style: none;
    padding-left: 0;
    margin: var(--spacing-md) 0;
}

.cfp-list li,
.challenge-list li {
    padding: var(--spacing-xs) 0;
    padding-left: 1.5rem;
    position: relative;
    margin-bottom: var(--spacing-sm);
}

.cfp-list li::before,
.challenge-list li::before {
    content: '•';
    position: absolute;
    left: 0.5rem;
    color: var(--color-primary);
    font-weight: 700;
    font-size: 1.25rem;
}

.dates-list li {
    padding: var(--spacing-xs) 0;
    border-left: 3px solid var(--color-primary);
    padding-left: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
}

.cfp-note {
    background-color: var(--color-background-gray);
    padding: var(--spacing-sm);
    border-left: 4px solid var(--color-primary);
    margin: var(--spacing-md) 0;
}

.cfp-dates {
    background-color: var(--color-background-gray);
    padding: var(--spacing-md);
    border-radius: 8px;
    margin: var(--spacing-md) 0;
}

.cfp-button-wrapper,
.challenge-button-wrapper {
    text-align: center;
    margin-top: var(--spacing-md);
}

.challenge-timeline {
    background-color: var(--color-background-gray);
    padding: var(--spacing-md);
    border-radius: 8px;
    margin: var(--spacing-md) 0;
}

/* ==========================================
   Contact Section
   ========================================== */
.contact-content {
    text-align: center;
}

.contact-email {
    font-size: var(--font-size-large);
    margin: var(--spacing-md) 0;
}

.social-links {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
    flex-wrap: wrap;
}

.social-links a {
    font-weight: 500;
}

.social-links .separator {
    color: var(--color-text-light);
}

/* ==========================================
   Footer
   ========================================== */
.footer {
    background-color: var(--color-background-dark);
    color: var(--color-background-gray);
    padding: var(--spacing-md) 0;
    text-align: center;
    font-size: var(--font-size-small);
}

.footer p {
    margin-bottom: var(--spacing-xs);
}

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

.visitor-counter {
    margin-top: var(--spacing-sm);
    display: flex;
    justify-content: center;
    align-items: center;
}

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

/* ==========================================
   Back to Top Button
   ========================================== */
.back-to-top {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    width: 48px;
    height: 48px;
    background-color: var(--color-primary);
    color: var(--color-background);
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px var(--color-shadow);
    transition: all var(--transition-speed);
    z-index: 999;
}

.back-to-top:hover {
    background-color: var(--color-primary-dark);
    transform: translateY(-4px);
}

.back-to-top:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

.back-to-top.show {
    display: flex;
}

/* ==========================================
   Responsive Design
   ========================================== */
@media (max-width: 1024px) {
    .organizers-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 768px) {
    /* Typography adjustments */
    h1 {
        font-size: 2rem;
    }
    
    h2 {
        font-size: 1.75rem;
    }
    
    h3 {
        font-size: 1.25rem;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.25rem;
    }
    
    /* Spacing adjustments */
    .section {
        padding: var(--spacing-md) 0;
    }
    
    .section-title {
        margin-bottom: var(--spacing-md);
    }
    
    /* Navigation */
    .nav-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: var(--nav-height);
        left: 0;
        right: 0;
        flex-direction: column;
        background-color: var(--color-background);
        border-bottom: 1px solid var(--color-border);
        padding: var(--spacing-sm) 0;
        gap: 0;
        max-height: 0;
        overflow: hidden;
        transition: max-height var(--transition-speed);
        box-shadow: 0 4px 8px var(--color-shadow);
    }
    
    .nav-menu.active {
        max-height: 500px;
    }
    
    .nav-menu li {
        width: 100%;
        text-align: center;
    }
    
    .nav-link {
        display: block;
        padding: var(--spacing-sm);
    }
    
    .nav-link.active::after {
        display: none;
    }
    
    /* Hamburger animation */
    .nav-toggle[aria-expanded="true"] .hamburger:nth-child(1) {
        transform: rotate(45deg) translate(6px, 6px);
    }
    
    .nav-toggle[aria-expanded="true"] .hamburger:nth-child(2) {
        opacity: 0;
    }
    
    .nav-toggle[aria-expanded="true"] .hamburger:nth-child(3) {
        transform: rotate(-45deg) translate(6px, -6px);
    }
    
    /* Hero */
    .hero {
        min-height: 60vh;
        padding: calc(var(--nav-height) + var(--spacing-md)) 0 var(--spacing-md);
    }
    
    .hero-buttons {
        flex-direction: column;
        align-items: stretch;
    }
    
    .btn {
        width: 100%;
    }
    
    /* Grids */
    .topics-grid {
        grid-template-columns: 1fr;
    }
    
    .speaker-card {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }
    
    .speaker-photo {
        width: 150px;
        height: 150px;
        min-width: 150px;
    }
    
    .organizers-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    /* Schedule table */
    .schedule-table {
        font-size: var(--font-size-small);
    }
    
    .schedule-table th,
    .schedule-table td {
        padding: var(--spacing-xs);
    }
    
    /* Back to top button */
    .back-to-top {
        bottom: 1rem;
        right: 1rem;
        width: 40px;
        height: 40px;
    }
}

@media (max-width: 480px) {
    :root {
        --spacing-md: 1rem;
        --spacing-lg: 2rem;
        --spacing-xl: 2.5rem;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .organizers-grid {
        grid-template-columns: 1fr;
    }
}

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

/* Focus visible for keyboard navigation */
:focus-visible {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* Skip to content link for screen readers */
.skip-to-content {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-primary);
    color: var(--color-background);
    padding: var(--spacing-xs) var(--spacing-sm);
    text-decoration: none;
    z-index: 100;
}

.skip-to-content:focus {
    top: 0;
}