/* Base Variables */
:root {
    --primary: #0f172a;
    /* Slate 900 */
    --primary-light: #334155;
    /* Slate 700 */
    --accent: #0ea5e9;
    /* Sky 500 */
    --accent-hover: #0284c7;
    /* Sky 600 */
    --alert: #f43f5e;
    /* Rose 500 */
    --background: #ffffff;
    --surface: #f8fafc;
    /* Slate 50 */
    --text: #1e293b;
    /* Slate 800 */
    --text-muted: #64748b;
    /* Slate 500 */
    --border: #e2e8f0;
    /* Slate 200 */

    --font-heading: 'Merriweather', serif;
    --font-body: 'Inter', sans-serif;

    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --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);

    --radius: 0.5rem;
    --transition: all 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    color: var(--text);
    background-color: var(--background);
    line-height: 1.6;
}

h1,
h2,
h3,
h4,
h5,
h6 {
    font-family: var(--font-heading);
    color: var(--primary);
    line-height: 1.2;
}

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

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

ul {
    list-style: none;
}

img {
    max-width: 100%;
    display: block;
}

/* Utilities */
.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-sm);
}

.section {
    padding: var(--spacing-xl) 0;
}

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

.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius);
    font-weight: 600;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    border: none;
}

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

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

.btn-secondary {
    background-color: transparent;
    border: 2px solid white;
    color: white;
}

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

/* Navbar */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
    background-color: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.logo {
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 1.5rem;
    color: white;
}

.nav-links {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-links a {
    color: #e2e8f0;
    font-weight: 500;
    font-size: 0.95rem;
}

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

.btn-nav {
    background-color: var(--accent);
    padding: 0.5rem 1rem;
    border-radius: var(--radius);
    color: white !important;
}

.btn-nav:hover {
    background-color: var(--accent-hover);
}

/* Hero Section */
.hero {
    position: relative;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
    color: white;
    padding-top: 60px;
    /* Navbar height */
    overflow: hidden;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image:
        radial-gradient(circle at 20% 80%, rgba(14, 165, 233, 0.15), transparent 40%),
        radial-gradient(circle at 80% 20%, rgba(244, 63, 94, 0.1), transparent 40%);
    z-index: 1;
}

.hero-content {
    position: relative;
    z-index: 2;
    max-width: 800px;
    padding: 0 1rem;
    animation: fadeIn 1s ease-out;
}

.conference-badge {
    display: inline-block;
    background-color: rgba(255, 255, 255, 0.1);
    padding: 0.25rem 0.75rem;
    border-radius: 2rem;
    font-size: 0.875rem;
    margin-bottom: 1rem;
    border: 1px solid rgba(255, 255, 255, 0.2);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.hero h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    color: white;
    line-height: 1.1;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: #94a3b8;
    margin-bottom: 2rem;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-bottom: 3rem;
}

.hero-details {
    display: flex;
    justify-content: center;
    gap: 2rem;
    font-size: 0.9rem;
    color: #cbd5e1;
}

.detail-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

/* Section Common */
.section-header {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.section-header h2 {
    font-size: 2.25rem;
    margin-bottom: 1rem;
}

.divider {
    height: 4px;
    width: 60px;
    background-color: var(--accent);
    margin: 0 auto;
    border-radius: 2px;
}

/* About */
.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    font-size: 1.1rem;
}

.about-content p {
    margin-bottom: 1.5rem;
}

/* Topics Grid */
.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: var(--spacing-lg);
}

.topic-card {
    background: white;
    padding: 2rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border);
    transition: var(--transition);
}

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

.topic-card h3 {
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

.topic-card p {
    color: var(--text-muted);
}

.cta-banner {
    text-align: center;
    background-color: var(--primary);
    color: white;
    padding: 3rem;
    border-radius: var(--radius);
}

.cta-banner h3 {
    color: white;
    margin-bottom: 1rem;
}

.cta-banner p {
    color: #cbd5e1;
    margin-bottom: 2rem;
}

/* Dates / Timeline */
.timeline {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    border-left: 2px solid var(--border);
    padding-left: 2rem;
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
}

.timeline-item::before {
    content: '';
    position: absolute;
    left: -2.45rem;
    top: 0.25rem;
    width: 1rem;
    height: 1rem;
    background: white;
    border: 3px solid var(--primary-light);
    border-radius: 50%;
}

.timeline-item.highlight::before {
    border-color: var(--alert);
    background: var(--alert);
}

.timeline-item .date {
    font-weight: 700;
    color: var(--accent);
    margin-bottom: 0.25rem;
}

.timeline-item .event {
    font-size: 1.25rem;
    font-weight: 500;
}

/* Organizers */
.organizers-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    text-align: center;
}

.organizer-card {
    padding: 1rem;
}

.organizer-img {
    width: 120px;
    height: 120px;
    object-fit: cover;
    border-radius: 50%;
    margin: 0 auto 1.5rem;
    box-shadow: var(--shadow-sm);
}

.organizer-card h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
}

.organizer-card p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

/* Footer */
.footer {
    background-color: var(--primary);
    color: #94a3b8;
    padding: 4rem 0 2rem;
}

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

.footer-logo {
    color: white;
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-links a {
    color: #cbd5e1;
}

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

/* Mobile Responsive */
.hamburger {
    display: none;
    cursor: pointer;
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .hamburger {
        display: block;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

    .hero-buttons {
        flex-direction: column;
    }

    .timeline {
        border-left: none;
        padding-left: 0;
    }

    .timeline-item::before {
        display: none;
    }

    .timeline-item {
        text-align: center;
        background: var(--surface);
        padding: 1.5rem;
        border-radius: var(--radius);
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}