/* ═══════════════════════════════════════
   Institute of Astronomy — Kharkiv University
   Styles
   ═══════════════════════════════════════ */

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

:root {
    --bg: #FAFAFA;
    --bg-card: #FFFFFF;
    --text: #1A1A2E;
    --text-secondary: #5A5A7A;
    --accent: #2D5BFF;
    --accent-light: #EBF0FF;
    --accent-warm: #D4380D;
    --accent-warm-bg: #FFF1EC;
    --border: #E8E8F0;
    --radius: 16px;
    --radius-sm: 10px;
    --shadow: 0 1px 3px rgba(0,0,0,0.04), 0 4px 12px rgba(0,0,0,0.04);
    --shadow-lg: 0 4px 6px rgba(0,0,0,0.04), 0 12px 40px rgba(0,0,0,0.08);
    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html { scroll-behavior: smooth; }

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
}

.container { max-width: 1200px; margin: 0 auto; padding: 0 24px; }


/* ── NAV ────────────────────────────── */

nav {
    position: fixed; top: 0; left: 0; right: 0; z-index: 100;
    background: rgba(250, 250, 250, 0.85);
    backdrop-filter: blur(20px); -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
}

nav .container {
    display: flex; align-items: center;
    justify-content: space-between; height: 72px;
}

.nav-logo {
    display: flex; align-items: center; gap: 12px;
    text-decoration: none; color: var(--text);
}

.nav-logo-icon {
    width: 40px; height: 40px; border-radius: 50%;
    background: linear-gradient(135deg, #2D5BFF 0%, #6B8AFF 100%);
    display: flex; align-items: center; justify-content: center;
    color: white; font-size: 18px;
}

.nav-logo img {
    width: 40px; height: 40px; border-radius: 50%; object-fit: cover;
}

.nav-logo span {
    font-weight: 600; font-size: 15px; letter-spacing: -0.02em;
}

.nav-links {
    display: flex; align-items: center; gap: 4px; list-style: none;
}

.nav-links a {
    text-decoration: none; color: var(--text-secondary);
    font-size: 14px; font-weight: 500;
    padding: 8px 14px; border-radius: 8px;
    transition: var(--transition);
}

.nav-links a:hover {
    color: var(--text); background: var(--accent-light);
}

.lang-toggle {
    display: flex; background: var(--bg);
    border: 1px solid var(--border);
    border-radius: 8px; overflow: hidden; margin-left: 8px;
}

.lang-toggle button {
    border: none; background: transparent;
    padding: 6px 14px; font-size: 13px; font-weight: 500;
    cursor: pointer; color: var(--text-secondary);
    transition: var(--transition); font-family: inherit;
}

.lang-toggle button.active {
    background: var(--accent); color: white;
}

.mobile-menu-btn {
    display: none; background: none; border: none;
    cursor: pointer; padding: 8px;
}

.mobile-menu-btn span {
    display: block; width: 22px; height: 2px;
    background: var(--text); margin: 5px 0; border-radius: 2px;
}


/* ── HERO ───────────────────────────── */

.hero {
    padding: 150px 0 80px; position: relative; overflow: hidden;
}

.hero::before {
    content: ''; position: absolute;
    top: -200px; right: -200px;
    width: 600px; height: 600px;
    background: radial-gradient(circle, rgba(45, 91, 255, 0.06) 0%, transparent 70%);
    border-radius: 50%;
}

.hero-content {
    position: relative; z-index: 1; max-width: 780px;
}

.hero-badge {
    display: inline-flex; align-items: center; gap: 8px;
    background: var(--accent-light); color: var(--accent);
    font-size: 13px; font-weight: 600; padding: 8px 16px;
    border-radius: 100px; margin-bottom: 28px; letter-spacing: 0.02em;
}

.hero h1 {
    font-family: 'Playfair Display', Georgia, serif;
    font-size: clamp(40px, 5vw, 64px); font-weight: 700;
    line-height: 1.1; letter-spacing: -0.03em; margin-bottom: 24px;
}

.hero p {
    font-size: 18px; color: var(--text-secondary);
    line-height: 1.7; max-width: 600px; margin-bottom: 40px;
}

.hero-actions { display: flex; gap: 16px; flex-wrap: wrap; }

.hero-banner-img {
    width: 100%; height: auto; display: block;
    border-radius: var(--radius); margin-bottom: 64px;
    box-shadow: var(--shadow-lg);
}


/* ── BUTTONS ────────────────────────── */

.btn {
    display: inline-flex; align-items: center; gap: 8px;
    padding: 14px 28px; border-radius: var(--radius-sm);
    font-size: 15px; font-weight: 600; text-decoration: none;
    transition: var(--transition); cursor: pointer;
    border: none; font-family: inherit;
}

.btn-primary {
    background: var(--accent); color: white;
    box-shadow: 0 2px 8px rgba(45, 91, 255, 0.3);
}

.btn-primary:hover {
    background: #1A45E0;
    box-shadow: 0 4px 16px rgba(45, 91, 255, 0.4);
    transform: translateY(-1px);
}

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

.btn-outline:hover {
    border-color: var(--accent); color: var(--accent);
    background: var(--accent-light);
}


/* ── ALERT BANNER ───────────────────── */

.alert-banner {
    background: var(--accent-warm-bg); border: 1px solid #FFD8C7;
    border-radius: var(--radius); padding: 24px 32px;
    display: flex; gap: 16px; align-items: flex-start;
    margin-bottom: 64px;
}

.alert-banner-icon { font-size: 24px; flex-shrink: 0; margin-top: 2px; }
.alert-banner h3 { font-size: 16px; font-weight: 600; color: var(--accent-warm); margin-bottom: 6px; }
.alert-banner p { font-size: 14px; color: var(--text-secondary); line-height: 1.6; }


/* ── STATS BAR ──────────────────────── */

.stats-bar {
    display: grid; grid-template-columns: repeat(4, 1fr); gap: 1px;
    background: var(--border); border-radius: var(--radius);
    overflow: hidden; margin-bottom: 80px; box-shadow: var(--shadow);
}

.stat-item { background: var(--bg-card); padding: 32px 24px; text-align: center; }

.stat-number {
    font-family: 'Playfair Display', Georgia, serif;
    font-size: 34px; font-weight: 700; color: var(--accent);
    letter-spacing: -0.02em;
}

.stat-label {
    font-size: 13px; color: var(--text-secondary);
    margin-top: 6px; font-weight: 500;
}


/* ── SECTIONS (shared) ──────────────── */

.section { padding: 80px 0; }
.section-header { margin-bottom: 48px; }

.section-label {
    font-size: 13px; font-weight: 600; text-transform: uppercase;
    letter-spacing: 0.08em; color: var(--accent); margin-bottom: 12px;
}

.section-title {
    font-family: 'Playfair Display', Georgia, serif;
    font-size: clamp(28px, 3.5vw, 42px); font-weight: 700;
    letter-spacing: -0.02em; margin-bottom: 16px;
}

.section-desc {
    font-size: 17px; color: var(--text-secondary);
    max-width: 620px; line-height: 1.7;
}

.section-divider {
    height: 1px; background: var(--border);
    max-width: 1200px; margin: 0 auto;
}


/* ── ABOUT ──────────────────────────── */

.about-grid {
    display: grid; grid-template-columns: 1fr 1fr;
    gap: 48px; align-items: start;
}

.about-image {
    border-radius: var(--radius); overflow: hidden;
    aspect-ratio: 4/3; background: #1A1A2E;
    display: flex; align-items: center;
    justify-content: center; position: relative;
}

.about-image img { width: 100%; height: 100%; object-fit: cover; }

.about-image .img-overlay {
    position: absolute; inset: 0;
    background: linear-gradient(180deg, transparent 50%, rgba(26,26,46,0.6) 100%);
}

.about-image .img-caption {
    position: absolute; bottom: 16px; left: 20px; right: 20px;
    color: white; font-size: 13px; font-weight: 500; opacity: 0.8;
}

.timeline { display: flex; flex-direction: column; gap: 20px; margin-top: 28px; }
.timeline-item { display: flex; gap: 16px; align-items: flex-start; }

.timeline-year {
    font-family: 'Playfair Display', Georgia, serif;
    font-weight: 700; font-size: 17px; color: var(--accent);
    min-width: 60px; padding-top: 2px;
}

.timeline-text {
    font-size: 15px; color: var(--text-secondary); line-height: 1.6;
    padding-bottom: 20px; border-bottom: 1px solid var(--border);
}

.timeline-item:last-child .timeline-text {
    border-bottom: none; padding-bottom: 0;
}


/* ── LEADERSHIP ─────────────────────── */

.leadership-grid {
    display: grid; grid-template-columns: repeat(4, 1fr);
    gap: 20px;
}

.leader-card {
    background: var(--bg-card); border-radius: var(--radius);
    padding: 28px 20px; border: 1px solid var(--border);
    text-align: center; transition: var(--transition);
    display: block;
    text-decoration: none;
    color: inherit;
}

.leader-card:hover { box-shadow: var(--shadow); }

.leader-avatar {
    width: 64px; height: 64px; border-radius: 50%;
    margin: 0 auto 16px;
    background: linear-gradient(135deg, var(--accent-light), #D4DCF5);
    display: flex; align-items: center; justify-content: center;
    font-size: 24px; color: var(--accent);
}

.leader-card h4 { font-size: 15px; font-weight: 600; margin-bottom: 4px; }
.leader-card .leader-role { font-size: 13px; color: var(--text-secondary); line-height: 1.5; }
.leader-card .leader-degree { font-size: 12px; color: var(--accent); font-weight: 500; margin-top: 8px; }


/* ── RESEARCH CARDS ─────────────────── */

.research-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }

.research-card {
    background: var(--bg-card);
    border-radius: var(--radius);
    padding: 32px 24px;
    border: 1px solid var(--border);
    transition: var(--transition);
    display: block;
    text-decoration: none;
    color: inherit;
}

.research-card:hover {
    box-shadow: var(--shadow-lg); border-color: transparent;
    transform: translateY(-4px);
}

.research-card-icon {
    width: 48px; height: 48px; border-radius: 14px;
    display: flex; align-items: center; justify-content: center;
    font-size: 22px; margin-bottom: 18px;
}

.research-card h3 { font-size: 17px; font-weight: 600; margin-bottom: 10px; letter-spacing: -0.01em; }
.research-card h3 a { color: inherit; text-decoration: none; transition: var(--transition); }
.research-card h3 a:hover { color: var(--accent); }
.research-card p { font-size: 14px; color: var(--text-secondary); line-height: 1.7; }

.research-card .card-leader {
    font-size: 13px; color: var(--accent); font-weight: 500;
    margin-top: 14px; padding-top: 14px;
    border-top: 1px solid var(--border);
}

.research-card-img {
    width: 100%; height: 140px; object-fit: cover;
    border-radius: var(--radius-sm); margin-bottom: 18px;
}

.icon-astro    { background: linear-gradient(135deg, #E0E8FF, #C4D0FF); }
.icon-astrom   { background: linear-gradient(135deg, #DDF5E8, #B8F0D0); }
.icon-asteroid { background: linear-gradient(135deg, #FFF3DD, #FFE8B8); }
.icon-planets  { background: linear-gradient(135deg, #FFE8DD, #FFD4BC); }
.icon-solar    { background: linear-gradient(135deg, #FFE0E0, #FFD0D0); }
.icon-station  { background: linear-gradient(135deg, #E8DDF5, #D4C0F0); }


/* ── INSTRUMENTS ────────────────────── */

.instruments-row {
    display: grid; grid-template-columns: repeat(3, 1fr);
    gap: 24px; margin-top: 40px;
}

.instrument-card {
    background: var(--bg-card); border-radius: var(--radius);
    padding: 28px; border: 1px solid var(--border);
    text-align: center; transition: var(--transition);
    display: block;
    text-decoration: none;
    color: inherit;
}

.instrument-card:hover { box-shadow: var(--shadow); }

.instrument-img-row {
    display: grid; grid-template-columns: 1fr 1fr;
    gap: 24px; margin-bottom: 32px;
}

.instrument-photo {
    border-radius: var(--radius); overflow: hidden;
    border: 1px solid var(--border); background: #f0f0f0;
}

.instrument-photo img {
    width: 100%; height: 200px; object-fit: cover; display: block;
}

.instrument-photo figcaption {
    padding: 12px 16px; font-size: 13px; color: var(--text-secondary);
}

.instrument-icon { font-size: 36px; margin-bottom: 14px; }
.instrument-card h4 { font-size: 16px; font-weight: 600; margin-bottom: 6px; }
.instrument-card p { font-size: 13px; color: var(--text-secondary); line-height: 1.5; }


/* ── EDUCATION ──────────────────────── */

.edu-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }

.edu-card {
    background: var(--bg-card); border-radius: var(--radius);
    padding: 28px 24px; border: 1px solid var(--border);
    transition: var(--transition);
}

.edu-card:hover { box-shadow: var(--shadow); transform: translateY(-2px); }
.edu-icon { font-size: 32px; margin-bottom: 14px; }
.edu-card h3 { font-size: 16px; font-weight: 600; margin-bottom: 8px; }
.edu-card p { font-size: 14px; color: var(--text-secondary); line-height: 1.6; }


/* ── RESOURCES ──────────────────────── */

.resources-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }

.resource-card {
    background: var(--bg-card); border-radius: var(--radius-sm);
    padding: 24px; border: 1px solid var(--border);
    transition: var(--transition); text-decoration: none; color: var(--text);
}

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

.resource-icon { font-size: 28px; margin-bottom: 12px; }
.resource-card h4 { font-size: 15px; font-weight: 600; margin-bottom: 6px; }
.resource-card p { font-size: 13px; color: var(--text-secondary); line-height: 1.5; }


/* ── CONTACT ────────────────────────── */

.contact-section {
    background: linear-gradient(180deg, var(--bg) 0%, #F0F0FA 100%);
    padding: 80px 0 100px;
}

.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; }
.contact-info { display: flex; flex-direction: column; gap: 24px; }
.contact-item { display: flex; gap: 16px; align-items: flex-start; }

.contact-icon {
    width: 44px; height: 44px; border-radius: 12px;
    background: var(--accent-light);
    display: flex; align-items: center; justify-content: center;
    color: var(--accent); font-size: 18px; flex-shrink: 0;
}

.contact-item h4 { font-size: 15px; font-weight: 600; margin-bottom: 4px; }
.contact-item p { font-size: 14px; color: var(--text-secondary); line-height: 1.5; }

.contact-map {
    border-radius: var(--radius); overflow: hidden;
    background: linear-gradient(135deg, #E8ECF8, #D0D8F0);
    aspect-ratio: 4/3; display: flex;
    align-items: center; justify-content: center;
    border: 1px solid var(--border);
}

.map-placeholder { text-align: center; color: var(--text-secondary); }
.map-placeholder svg { width: 48px; height: 48px; opacity: 0.4; margin-bottom: 12px; }


/* ── FOOTER ─────────────────────────── */

footer {
    background: var(--text); color: rgba(255,255,255,0.7);
    padding: 56px 0 32px;
}

.footer-grid {
    display: grid; grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 40px; margin-bottom: 48px;
}

.footer-brand { display: flex; align-items: center; gap: 12px; margin-bottom: 16px; }

.footer-brand-icon {
    width: 36px; height: 36px; border-radius: 50%;
    background: linear-gradient(135deg, #2D5BFF, #6B8AFF);
    display: flex; align-items: center; justify-content: center;
    color: white; font-size: 16px;
}

.footer-brand img {
    width: 36px; height: 36px; border-radius: 50%; object-fit: cover;
}

.footer-brand span { font-weight: 600; color: white; font-size: 15px; }
footer p { font-size: 14px; line-height: 1.7; }

.footer-heading {
    font-size: 13px; font-weight: 600; color: white;
    margin-bottom: 16px; text-transform: uppercase;
    letter-spacing: 0.05em;
}

.footer-links {
    list-style: none; display: flex;
    flex-direction: column; gap: 10px;
}

.footer-links a {
    color: rgba(255,255,255,0.6); text-decoration: none;
    font-size: 14px; transition: var(--transition);
}

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

.footer-bottom {
    border-top: 1px solid rgba(255,255,255,0.1);
    padding-top: 24px; display: flex;
    justify-content: space-between; align-items: center;
    font-size: 13px;
}


/* ── RESPONSIVE ─────────────────────── */

@media (max-width: 1024px) {
    .research-grid,
    .leadership-grid { grid-template-columns: repeat(2, 1fr); }
    .resources-grid   { grid-template-columns: repeat(2, 1fr); }
    .footer-grid      { grid-template-columns: 1fr 1fr; gap: 32px; }
}

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

    .nav-links.open {
        display: flex; flex-direction: column;
        position: absolute; top: 72px; left: 0; right: 0;
        background: var(--bg-card);
        border-bottom: 1px solid var(--border);
        padding: 16px 24px; box-shadow: var(--shadow-lg);
    }

    .hero { padding: 120px 0 60px; }
    .stats-bar { grid-template-columns: repeat(2, 1fr); }

    .about-grid,
    .contact-grid     { grid-template-columns: 1fr; }

    .research-grid,
    .edu-grid,
    .instruments-row,
    .instrument-img-row { grid-template-columns: 1fr; }

    .leadership-grid  { grid-template-columns: 1fr 1fr; }
    .resources-grid   { grid-template-columns: 1fr; }
    .footer-grid      { grid-template-columns: 1fr; }

    .footer-bottom {
        flex-direction: column; gap: 12px; text-align: center;
    }

    .hero-actions { flex-direction: column; }
    .btn { justify-content: center; }
    .alert-banner { flex-direction: column; }
}


/* ── ANIMATIONS ─────────────────────── */

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

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