/* === Variables === */
:root {
    --color-primary: #0f172a;
    --color-primary-mid: #1e293b;
    --color-accent: #06b6d4;
    --color-accent-dim: #0891b2;
    --color-accent-glow: rgba(6, 182, 212, 0.15);
    --color-warm: #f59e0b;
    --color-bg: #ffffff;
    --color-bg-alt: #f8fafc;
    --color-surface: #ffffff;
    --color-text: #334155;
    --color-text-light: #64748b;
    --color-heading: #0f172a;
    --color-border: #e2e8f0;
    --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-heading: 'Space Grotesk', 'Inter', sans-serif;
    --container-width: 960px;
    --nav-height: 64px;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--nav-height);
}

body {
    font-family: var(--font-body);
    color: var(--color-text);
    line-height: 1.7;
    background: var(--color-bg);
    -webkit-font-smoothing: antialiased;
}

/* === Scroll Reveal === */
.fade-in {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* stagger children */
.topics-grid .fade-in:nth-child(2) { transition-delay: 0.08s; }
.topics-grid .fade-in:nth-child(3) { transition-delay: 0.16s; }
.topics-grid .fade-in:nth-child(4) { transition-delay: 0.24s; }
.speakers-grid .fade-in:nth-child(2) { transition-delay: 0.08s; }
.speakers-grid .fade-in:nth-child(3) { transition-delay: 0.16s; }
.speakers-grid .fade-in:nth-child(4) { transition-delay: 0.24s; }
.program-topics .fade-in:nth-child(2) { transition-delay: 0.06s; }
.program-topics .fade-in:nth-child(3) { transition-delay: 0.12s; }
.program-topics .fade-in:nth-child(4) { transition-delay: 0.18s; }
.program-topics .fade-in:nth-child(5) { transition-delay: 0.24s; }
.program-topics .fade-in:nth-child(6) { transition-delay: 0.30s; }
.program-topics .fade-in:nth-child(7) { transition-delay: 0.36s; }

/* === Navigation === */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: transparent;
    transition: background 0.3s, box-shadow 0.3s;
}

.navbar.scrolled {
    background: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(12px);
    box-shadow: 0 1px 0 rgba(255, 255, 255, 0.05);
}

.nav-container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: var(--nav-height);
}

.nav-brand {
    color: #fff;
    text-decoration: none;
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 1.15rem;
    letter-spacing: -0.01em;
    display: flex;
    align-items: center;
    gap: 0.55rem;
}

.nav-brand-logo {
    width: 44px;
    height: 44px;
    object-fit: contain;
    flex-shrink: 0;
}

.nav-year {
    color: var(--color-accent);
}

.nav-links {
    list-style: none;
    display: flex;
    gap: 0.25rem;
}

.nav-links a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    font-size: 0.85rem;
    font-weight: 500;
    padding: 0.4rem 0.75rem;
    transition: color 0.2s;
}

.nav-links a:hover {
    color: #fff;
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    display: block;
    width: 22px;
    height: 2px;
    background: #fff;
    margin: 5px 0;
    transition: 0.2s;
}

/* === Hero === */
.hero {
    position: relative;
    background: linear-gradient(160deg, #0f172a 0%, #1e3a5f 40%, #0c4a6e 70%, #134e4a 100%);
    color: #fff;
    text-align: center;
    padding: 8rem 2rem 5rem;
    min-height: 520px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

#hero-canvas {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

.hero-content {
    position: relative;
    max-width: var(--container-width);
}

.hero-title-row {
    display: flex;
    flex-direction: row;
    flex-wrap: nowrap;
    align-items: center;
    justify-content: center;
    gap: 1.5rem;
    margin-bottom: 0.75rem;
}

.hero-logo {
    width: 130px;
    height: 130px;
    object-fit: contain;
    flex-shrink: 0;
    filter: drop-shadow(0 8px 28px rgba(6, 182, 212, 0.35));
}

.hero-title-row h1 {
    margin-bottom: 0;
    text-align: left;
}

.hero-label {
    display: inline-block;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.2em;
    margin-bottom: 1.25rem;
    color: var(--color-accent);
    border: 1px solid rgba(6, 182, 212, 0.3);
    padding: 0.35rem 1rem;
}

.hero h1 {
    font-family: var(--font-heading);
    font-size: 3.5rem;
    font-weight: 700;
    line-height: 1.1;
    margin-bottom: 0.75rem;
    letter-spacing: -0.02em;
}

.hero-subtitle {
    font-size: 1.15rem;
    opacity: 0.75;
    margin-bottom: 2rem;
    font-weight: 400;
    font-style: italic;
}

.hero-details {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1.5rem;
}

.hero-detail-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.95rem;
    font-weight: 500;
    opacity: 0.9;
}

.hero-detail-item svg {
    opacity: 0.7;
    flex-shrink: 0;
}

.hero-funding {
    font-size: 0.8rem;
    opacity: 0.45;
    margin-top: 2rem;
    letter-spacing: 0.04em;
}

/* === Sections === */
.section {
    padding: 5rem 2rem;
}

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

.container {
    max-width: var(--container-width);
    margin: 0 auto;
}

.section-header {
    margin-bottom: 0.5rem;
}

.section h2 {
    font-family: var(--font-heading);
    font-size: 2rem;
    color: var(--color-heading);
    margin-bottom: 1rem;
    letter-spacing: -0.02em;
    position: relative;
    display: inline-block;
}

.section h2::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 40px;
    height: 3px;
    background: var(--color-accent);
}

.section-intro {
    color: var(--color-text-light);
    margin-bottom: 2rem;
    font-size: 1.05rem;
}

/* === About: Topic Cards === */
.topics-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.25rem;
    margin: 2.5rem 0;
}

.topic-card {
    background: var(--color-surface);
    padding: 1.75rem;
    border: 1px solid var(--color-border);
    position: relative;
    transition: border-color 0.25s, box-shadow 0.25s;
}

.topic-card:hover {
    border-color: var(--color-accent);
    box-shadow: 0 0 0 1px var(--color-accent), 0 8px 24px -8px rgba(6, 182, 212, 0.12);
}

.topic-icon {
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-accent-glow);
    margin-bottom: 1rem;
    color: var(--color-accent-dim);
}

.topic-card h3 {
    font-family: var(--font-heading);
    font-size: 1rem;
    color: var(--color-heading);
    margin-bottom: 0.5rem;
    letter-spacing: -0.01em;
}

.topic-card p {
    font-size: 0.9rem;
    color: var(--color-text-light);
    line-height: 1.55;
}

/* === Speakers === */
.speakers-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.25rem;
    margin-top: 1.5rem;
}

.speaker-card {
    background: var(--color-surface);
    padding: 1.75rem;
    text-align: center;
    border: 1px solid var(--color-border);
    position: relative;
    overflow: hidden;
    transition: border-color 0.25s, transform 0.25s;
}

.speaker-card:hover {
    border-color: var(--color-accent);
    transform: translateY(-2px);
}

.speaker-accent {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--color-accent), var(--color-accent-dim));
}

.speaker-photo {
    width: 300px;
    height: 300px;
    object-fit: cover;
    margin: 0 auto 1rem;
    display: block;
}

.speaker-photo.placeholder {
    background: var(--color-bg-alt);
    border: 1px dashed var(--color-border);
}

.speaker-card h3 {
    font-family: var(--font-heading);
    font-size: 1.05rem;
    color: var(--color-heading);
    margin-bottom: 0.25rem;
    letter-spacing: -0.01em;
}

.speaker-card h3 a {
    color: inherit;
    text-decoration: none;
    transition: color 0.2s;
}

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

.speaker-card h3 a::after {
    content: '';
    position: absolute;
    inset: 0;
}

.speaker-affiliation {
    font-size: 0.85rem;
    color: var(--color-text-light);
    margin-bottom: 0.75rem;
}

.speaker-topic {
    display: inline-block;
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--color-accent-dim);
    background: var(--color-accent-glow);
    padding: 0.25rem 0.85rem;
    letter-spacing: 0.01em;
}

/* === Program === */
.program-topics {
    position: relative;
    padding-left: 2rem;
}

/* vertical timeline line */
.program-topics::before {
    content: '';
    position: absolute;
    left: 7px;
    top: 8px;
    bottom: 8px;
    width: 2px;
    background: var(--color-border);
}

.program-slot {
    display: flex;
    align-items: flex-start;
    padding: 1rem 0 1rem 1rem;
    position: relative;
}

.slot-marker {
    position: absolute;
    left: -2rem;
    top: 1.25rem;
    width: 16px;
    height: 16px;
    border: 2px solid var(--color-accent);
    background: var(--color-bg);
    flex-shrink: 0;
}

.slot-social .slot-marker {
    background: var(--color-accent);
}

.slot-content {
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
    padding: 0.75rem 1.25rem;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    width: 100%;
    transition: border-color 0.2s;
}

.slot-content:hover {
    border-color: var(--color-accent);
}

.slot-content strong {
    font-family: var(--font-heading);
    color: var(--color-heading);
    font-size: 0.95rem;
    letter-spacing: -0.01em;
}

.slot-content span {
    font-size: 0.85rem;
    color: var(--color-text-light);
}

/* === Venue === */
.venue-info {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2.5rem;
    margin-top: 1.5rem;
}

.venue-main, .venue-travel {
    padding: 1.5rem;
    border: 1px solid var(--color-border);
    background: var(--color-surface);
}

.venue-info h3 {
    font-family: var(--font-heading);
    font-size: 1.1rem;
    color: var(--color-heading);
    margin-bottom: 0.5rem;
}

.venue-travel ul {
    list-style: none;
    margin-top: 0.75rem;
}

.venue-travel li {
    padding: 0.4rem 0 0.4rem 1.25rem;
    position: relative;
    font-size: 0.93rem;
}

.venue-travel li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0.75rem;
    width: 6px;
    height: 6px;
    background: var(--color-accent);
}

/* === Registration === */
.registration-box {
    background: var(--color-surface);
    border: 2px solid var(--color-border);
    padding: 3rem;
    text-align: center;
    margin-top: 1.5rem;
    position: relative;
}

.registration-box::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--color-accent), var(--color-warm));
}

.registration-status {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-accent-dim);
    margin-bottom: 1rem;
    letter-spacing: -0.02em;
}

.registration-box p {
    max-width: 550px;
    margin-left: auto;
    margin-right: auto;
}

.registration-box p + p {
    margin-top: 0.75rem;
}

.registration-cta {
    margin-top: 2rem !important;
}

.btn-primary {
    display: inline-block;
    background: var(--color-accent);
    color: #fff;
    padding: 0.9rem 2.25rem;
    font-family: var(--font-heading);
    font-weight: 600;
    font-size: 1rem;
    letter-spacing: 0.02em;
    text-decoration: none;
    border: 2px solid var(--color-accent);
    transition: background 0.2s ease, border-color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
}

.btn-primary:hover,
.btn-primary:focus {
    background: var(--color-accent-dim);
    border-color: var(--color-accent-dim);
    transform: translateY(-1px);
    box-shadow: 0 6px 20px var(--color-accent-glow);
    color: #fff;
}

.registration-fineprint {
    margin-top: 1.5rem !important;
    font-size: 0.85rem;
    color: var(--color-text-light);
}

/* === Footer === */
.footer {
    background: var(--color-primary);
    color: rgba(255, 255, 255, 0.8);
    text-align: center;
}

.footer h2 {
    color: #fff;
}

.footer h2::after {
    background: var(--color-accent);
}

.footer a {
    color: var(--color-accent);
    text-decoration: underline;
    text-underline-offset: 2px;
}

.footer a:hover {
    color: #fff;
}

.organizers {
    margin-bottom: 2.5rem;
}

.organizers strong {
    color: #fff;
}



.funding {
    font-size: 0.85rem;
    opacity: 0.85;
    max-width: 600px;
    margin: 0 auto 1.5rem;
}

.funding-logos {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 2.5rem;
    margin-bottom: 1.25rem;
}

.funding-logo {
    height: 48px;
    width: auto;
    opacity: 0.9;
}

.copyright {
    font-size: 0.8rem;
    opacity: 0.4;
    padding-top: 1.5rem;
    border-top: 1px solid rgba(255, 255, 255, 0.08);
}

/* === Responsive === */
@media (max-width: 768px) {
    .nav-toggle {
        display: block;
    }

    .nav-links {
        display: none;
        position: absolute;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: rgba(15, 23, 42, 0.98);
        backdrop-filter: blur(12px);
        flex-direction: column;
        padding: 1rem 2rem 1.5rem;
        gap: 0.25rem;
    }

    .nav-links.open {
        display: flex;
    }

    .nav-links a {
        padding: 0.5rem 0;
    }

    .hero {
        padding: 6rem 1.5rem 3.5rem;
        min-height: auto;
    }

    .hero-title-row {
        flex-direction: column;
        gap: 1rem;
    }

    .hero-logo {
        width: 120px;
        height: 120px;
    }

    .hero-title-row h1 {
        text-align: center;
    }

    .hero h1 {
        font-size: 2.25rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .hero-details {
        flex-direction: column;
        gap: 0.5rem;
    }

    .topics-grid,
    .speakers-grid {
        grid-template-columns: 1fr;
    }

    .venue-info {
        grid-template-columns: 1fr;
    }

    .section {
        padding: 3.5rem 1.25rem;
    }

    .section h2 {
        font-size: 1.6rem;
    }

    .funding-logos {
        flex-direction: column;
        gap: 1.5rem;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 1.85rem;
    }

    .section h2 {
        font-size: 1.4rem;
    }

    .registration-box {
        padding: 2rem 1.25rem;
    }

    .program-topics {
        padding-left: 1.5rem;
    }
}