/* =============================================
   BELFAST SWIFT — THEME DEFINITIONS
   Theme 1: Swift/Apple (dark, orange accent)
   Theme 4: Belfast (dark green, gold accent)
   ============================================= */

:root,
[data-theme="swift"] {
    --bg-primary:       #000000;
    --bg-secondary:     #111111;
    --bg-card:          #1C1C1E;
    --bg-card-hover:    #2C2C2E;

    --text-primary:     #FFFFFF;
    --text-secondary:   rgba(235, 235, 245, 0.6);
    --text-tertiary:    rgba(235, 235, 245, 0.50);

    --accent:           #FF6B2B;
    --accent-alt:       #FF2D55;
    --accent-hover:     #FF8C55;

    --border:           rgba(255, 255, 255, 0.08);
    --border-accent:    rgba(255, 107, 43, 0.35);

    --hero-glow-a:      rgba(255, 107, 43, 0.12);
    --hero-glow-b:      rgba(255, 45, 85, 0.08);

    --btn-primary-bg:   #FF6B2B;
    --btn-primary-fg:   #FFFFFF;
    --btn-outline-fg:   #FFFFFF;
    --btn-outline-bd:   rgba(255, 255, 255, 0.3);

    --badge-bg:         rgba(255, 107, 43, 0.12);
    --badge-fg:         #FF8C55;
    --badge-bd:         rgba(255, 107, 43, 0.3);

    --timeline-dot:     #FF6B2B;
    --stat-fg:          #FF6B2B;

    --nav-bg:           rgba(0, 0, 0, 0.75);
    --card-shadow:      0 12px 40px rgba(0, 0, 0, 0.5);

    --radius:    16px;
    --radius-sm:  8px;
    --radius-xs:  6px;
}

[data-theme="belfast"] {
    --bg-primary:       #0C1A0C;
    --bg-secondary:     #142114;
    --bg-card:          #1C3020;
    --bg-card-hover:    #264228;

    --text-primary:     #FFFFFF;
    --text-secondary:   rgba(255, 255, 255, 0.62);
    --text-tertiary:    rgba(255, 255, 255, 0.50);

    --accent:           #D4AF37;
    --accent-alt:       #007A33;
    --accent-hover:     #EFD060;

    --border:           rgba(212, 175, 55, 0.12);
    --border-accent:    rgba(212, 175, 55, 0.4);

    --hero-glow-a:      rgba(0, 122, 51, 0.18);
    --hero-glow-b:      rgba(212, 175, 55, 0.12);

    --btn-primary-bg:   #D4AF37;
    --btn-primary-fg:   #0C1A0C;
    --btn-outline-fg:   #D4AF37;
    --btn-outline-bd:   rgba(212, 175, 55, 0.4);

    --badge-bg:         rgba(0, 122, 51, 0.18);
    --badge-fg:         #7FD09F;
    --badge-bd:         rgba(0, 122, 51, 0.4);

    --timeline-dot:     #D4AF37;
    --stat-fg:          #D4AF37;

    --nav-bg:           rgba(12, 26, 12, 0.8);
    --card-shadow:      0 12px 40px rgba(0, 0, 0, 0.55);

    --radius:    16px;
    --radius-sm:  8px;
    --radius-xs:  6px;
}

/* =============================================
   SKIP LINK
   ============================================= */

.skip-link {
    position: absolute;
    top: -100%;
    left: 16px;
    z-index: 999;
    padding: 8px 16px;
    background: var(--accent);
    color: var(--btn-primary-fg);
    border-radius: var(--radius-sm);
    font-weight: 600;
    transition: top 0.2s ease;
}

.skip-link:focus {
    top: 16px;
    outline: 2px solid var(--btn-primary-fg);
    outline-offset: 2px;
}

/* =============================================
   FOCUS STYLES
   ============================================= */

:focus {
    outline: none;
}

:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 3px;
    border-radius: 4px;
}

/* =============================================
   RESET & BASE
   ============================================= */

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

html {
    scroll-behavior: smooth;
    background-color: var(--bg-primary);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', system-ui, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    transition: background-color 0.4s ease, color 0.4s ease;
}

a {
    text-decoration: none;
    color: inherit;
}

h1, h2, h3 {
    line-height: 1.1;
}

/* =============================================
   LAYOUT
   ============================================= */

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

.section {
    padding: 96px 0;
}

.section__header {
    text-align: center;
    margin-bottom: 64px;
}

.section__title {
    font-size: clamp(2rem, 4vw, 2.75rem);
    font-weight: 800;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.section__subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

/* =============================================
   BUTTONS
   ============================================= */

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 14px 28px;
    border-radius: 100px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.2s ease, transform 0.2s ease, background 0.4s ease, color 0.4s ease, border-color 0.4s ease;
    border: none;
    white-space: nowrap;
}

.btn--primary {
    background: var(--btn-primary-bg);
    color: var(--btn-primary-fg);
}

.btn--primary:hover {
    opacity: 0.88;
    transform: translateY(-2px);
}

.btn--secondary {
    background: transparent;
    color: var(--btn-outline-fg);
    border: 1.5px solid var(--btn-outline-bd);
}

.btn--secondary:hover {
    background: var(--border);
    transform: translateY(-2px);
}

.btn--large {
    padding: 18px 44px;
    font-size: 1.125rem;
}

/* =============================================
   NAVIGATION
   ============================================= */

.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: var(--nav-bg);
    backdrop-filter: blur(24px);
    -webkit-backdrop-filter: blur(24px);
    border-bottom: 1px solid var(--border);
    transition: background-color 0.4s ease, border-color 0.4s ease;
    padding-top: env(safe-area-inset-top, 0px);
}

.nav__container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 16px 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav__logo,
a.nav__logo {
    font-size: 1.25rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-primary);
    text-decoration: none;
}

.nav__logo-icon {
    font-size: 1.1rem;
}

.swift-icon {
    width: 20px;
    height: 20px;
    flex-shrink: 0;
}

.nav__right {
    display: flex;
    align-items: center;
    gap: 12px;
}

.nav__cta {
    display: inline-flex;
    padding: 8px 16px;
    background: var(--btn-primary-bg);
    color: var(--btn-primary-fg);
    border-radius: 100px;
    font-size: 0.875rem;
    font-weight: 600;
    transition: opacity 0.2s ease, background 0.4s ease, color 0.4s ease;
    cursor: pointer;
}

.nav__cta:hover {
    opacity: 0.88;
}

.hero {
    position: relative;
    min-height: 100vh;
    min-height: 100svh;
    display: flex;
    align-items: center;
    padding: calc(120px + env(safe-area-inset-top, 0px)) 24px 80px;
    overflow: hidden;
}

.hero__bg {
    position: absolute;
    inset: 0;
    pointer-events: none;
    transition: background 0.4s ease;
}

.hero__bg::before {
    content: '';
    position: absolute;
    top: 10%;
    left: -15%;
    width: 70%;
    height: 70%;
    background: radial-gradient(circle, var(--hero-glow-a) 0%, transparent 65%);
    border-radius: 50%;
    transition: background 0.4s ease;
}

.hero__bg::after {
    content: '';
    position: absolute;
    bottom: 5%;
    right: -10%;
    width: 50%;
    height: 50%;
    background: radial-gradient(circle, var(--hero-glow-b) 0%, transparent 65%);
    border-radius: 50%;
    transition: background 0.4s ease;
}

.hero__container {
    position: relative;
    z-index: 1;
    max-width: 1100px;
    margin: 0 auto;
    width: 100%;
}

.hero__badge {
    display: inline-flex;
    align-items: center;
    background: var(--badge-bg);
    color: var(--badge-fg);
    border: 1px solid var(--badge-bd);
    padding: 6px 16px;
    border-radius: 100px;
    font-size: 0.8125rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    margin-bottom: 32px;
    transition: background 0.4s ease, color 0.4s ease, border-color 0.4s ease;
}

.hero__title-row {
    display: flex;
    align-items: center;
    gap: clamp(24px, 4vw, 56px);
    margin-bottom: 28px;
}

.hero__logo {
    height: clamp(140px, 22vw, 260px);
    width: auto;
    flex-shrink: 0;
    border-radius: var(--radius);
}

.hero__title {
    font-size: clamp(2.5rem, 12vw, 9rem);
    font-weight: 900;
    letter-spacing: -0.04em;
    line-height: 0.92;
    margin-bottom: 0;
    color: var(--text-primary);
}

.hero__title-accent {
    color: var(--accent);
    transition: color 0.4s ease;
}

.hero__subtitle {
    font-size: clamp(1.0625rem, 2vw, 1.25rem);
    color: var(--text-secondary);
    max-width: 500px;
    margin-bottom: 48px;
    line-height: 1.65;
}

.hero__event-details {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 48px;
}

.hero__detail {
    display: flex;
    align-items: center;
    gap: 10px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    padding: 11px 18px;
    border-radius: var(--radius-sm);
    font-size: 0.9375rem;
    font-weight: 500;
    transition: background 0.4s ease, border-color 0.4s ease;
}

.hero__actions {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 16px;
}

.hero__email-fallback {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.hero__email-link {
    color: var(--accent);
    text-decoration: underline;
    text-decoration-color: var(--border-accent);
    text-underline-offset: 3px;
    transition: color 0.2s ease, text-decoration-color 0.2s ease;
}

.hero__email-link:hover {
    color: var(--accent-hover);
    text-decoration-color: var(--accent-hover);
}

/* =============================================
   ABOUT
   ============================================= */

.about {
    background: var(--bg-secondary);
    transition: background-color 0.4s ease;
}

.about__content {
    max-width: 700px;
    margin: 0 auto 64px;
    text-align: center;
}

.about__text {
    font-size: 1.0625rem;
    color: var(--text-secondary);
    margin-bottom: 20px;
    line-height: 1.8;
}

.about__stats {
    display: flex;
    justify-content: center;
    gap: 64px;
    flex-wrap: wrap;
}

.stat__number {
    font-size: 3rem;
    font-weight: 900;
    color: var(--stat-fg);
    line-height: 1;
    margin-bottom: 8px;
    transition: color 0.4s ease;
}

.stat__label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
}

/* =============================================
   SPEAKERS
   ============================================= */

.speakers {
    background: var(--bg-primary);
    transition: background-color 0.4s ease;
}

.speakers__grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 24px;
}

.speaker-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 36px;
    display: flex;
    flex-direction: column;
    gap: 20px;
    transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease, background-color 0.4s ease;
}

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

.speaker-card__avatar {
    width: 68px;
    height: 68px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--accent), var(--accent-alt));
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    font-weight: 800;
    color: white;
    flex-shrink: 0;
    transition: background 0.4s ease;
}

.speaker-card__name {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 4px;
}

.speaker-card__talk {
    color: var(--accent);
    font-weight: 600;
    font-size: 0.9375rem;
    margin-bottom: 12px;
    transition: color 0.4s ease;
}

.speaker-card__bio {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    line-height: 1.65;
}

/* =============================================
   SCHEDULE
   ============================================= */

.schedule {
    background: var(--bg-secondary);
    transition: background-color 0.4s ease;
}

.timeline {
    max-width: 640px;
    margin: 0 auto;
    position: relative;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 88px;
    top: 6px;
    bottom: 6px;
    width: 1px;
    background: var(--border);
    transition: background 0.4s ease;
}

.timeline__item {
    display: grid;
    grid-template-columns: 88px 20px 1fr;
    column-gap: 20px;
    padding-bottom: 36px;
    align-items: start;
}

.timeline__item:last-child {
    padding-bottom: 0;
}

.timeline__time {
    text-align: right;
    color: var(--text-secondary);
    font-size: 0.8125rem;
    font-weight: 600;
    padding-top: 2px;
    font-variant-numeric: tabular-nums;
    line-height: 1.4;
}

.timeline__dot {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: var(--timeline-dot);
    margin-top: 3px;
    position: relative;
    z-index: 1;
    flex-shrink: 0;
    box-shadow: 0 0 0 3px var(--bg-secondary), 0 0 0 4px var(--timeline-dot);
    transition: background 0.4s ease, box-shadow 0.4s ease;
}

.timeline__content h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 2px;
}

.timeline__content p {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

/* =============================================
   VENUE
   ============================================= */

.venue {
    background: var(--bg-primary);
    transition: background-color 0.4s ease;
}

.venue__content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 56px;
    align-items: start;
}

.venue__name {
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.venue__address-link,
.hero__detail-link {
    color: inherit;
    text-decoration: underline;
    text-decoration-color: var(--border-accent);
    text-underline-offset: 3px;
    transition: color 0.2s ease, text-decoration-color 0.2s ease;
}

.venue__address-link:hover,
.hero__detail-link:hover {
    color: var(--accent);
    text-decoration-color: var(--accent);
}

.venue__address {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
    margin-bottom: 20px;
    font-size: 0.9375rem;
}

.venue__description {
    color: var(--text-secondary);
    line-height: 1.75;
    margin-bottom: 28px;
    font-size: 0.9375rem;
}

.venue__map {
    border-radius: var(--radius);
    overflow: hidden;
    border: 1px solid var(--border);
    transition: border-color 0.4s ease;
}

.venue__map iframe {
    display: block;
    filter: grayscale(20%) brightness(0.85);
    transition: filter 0.3s ease;
}

.venue__map:hover iframe {
    filter: grayscale(0%) brightness(1);
}

/* =============================================
   RSVP
   ============================================= */

.rsvp {
    background: var(--bg-secondary);
    text-align: center;
    transition: background-color 0.4s ease;
}

.rsvp__content {
    max-width: 520px;
    margin: 0 auto;
}

.rsvp__badge {
    display: inline-block;
    background: var(--badge-bg);
    color: var(--badge-fg);
    border: 1px solid var(--badge-bd);
    padding: 5px 14px;
    border-radius: 100px;
    font-size: 0.8125rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.04em;
    margin-bottom: 24px;
    transition: background 0.4s ease, color 0.4s ease, border-color 0.4s ease;
}

.rsvp__title {
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 900;
    margin-bottom: 16px;
}

.rsvp__subtitle {
    font-size: 1.0625rem;
    color: var(--text-secondary);
    margin-bottom: 40px;
    line-height: 1.65;
}

.rsvp__note {
    margin-top: 20px;
    color: var(--text-tertiary);
    font-size: 0.875rem;
}

/* =============================================
   FOOTER
   ============================================= */

.footer {
    background: var(--bg-primary);
    border-top: 1px solid var(--border);
    padding: 48px 0 calc(48px + env(safe-area-inset-bottom, 0px));
    transition: background-color 0.4s ease, border-color 0.4s ease;
}

.footer__content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 28px;
    flex-wrap: wrap;
    gap: 20px;
}

.footer__logo,
a.footer__logo {
    font-size: 1.125rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-primary);
    text-decoration: none;
}

.footer__social {
    display: flex;
    gap: 12px;
}

.footer__social-link {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 42px;
    height: 42px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 50%;
    color: var(--text-secondary);
    font-size: 0.9375rem;
    font-weight: 700;
    transition: border-color 0.2s ease, color 0.2s ease, background-color 0.4s ease;
}

.footer__social-link:hover {
    border-color: var(--accent);
    color: var(--accent);
}

.footer__bottom {
    text-align: center;
    color: var(--text-tertiary);
    font-size: 0.875rem;
}

.footer__trademark {
    margin-top: 6px;
    font-size: 0.75rem;
}

/* =============================================
   RESPONSIVE
   ============================================= */

@media (max-width: 900px) {
    .venue__content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .nav__cta {
        padding: 8px 16px;
    }

    .section {
        padding: 64px 0;
    }

    .hero {
        padding: calc(100px + env(safe-area-inset-top, 0px)) 24px 64px;
    }

    .hero__title-row {
        flex-direction: column;
        align-items: flex-start;
        gap: 24px;
    }

    .hero__logo {
        height: clamp(100px, 40vw, 160px);
    }

    .about__stats {
        gap: 40px;
    }

    .stat__number {
        font-size: 2rem;
    }

    .theme-toggle .theme-toggle__text {
        display: none;
    }
}

@media (max-width: 480px) {
    .hero__event-details {
        flex-direction: column;
    }

    .hero__actions {
        flex-direction: column;
        align-items: flex-start;
    }

    .speakers__grid {
        grid-template-columns: 1fr;
    }

    .timeline::before {
        display: none;
    }

    .timeline__item {
        grid-template-columns: auto 1fr;
        column-gap: 12px;
    }

    .timeline__dot {
        display: none;
    }

    .timeline__time {
        text-align: left;
        color: var(--accent);
        transition: color 0.4s ease;
    }
}

/* =============================================
   REDUCED MOTION
   ============================================= */

@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    html {
        scroll-behavior: auto;
    }
}