:root {
    color-scheme: light;
    font-family: Helvetica,Verdana,sans-serif;
    --bg: #f5f7fa;
    --surface: #ffffff;
    --surface-strong: #f8fafc;
    --text: #1f2937;
    --muted: #4b5563;
    --border: #e2e8f0;
    --shadow: rgba(15, 23, 42, 0.12);
    --card-shadow: rgba(15, 23, 42, 0.08);
    --link-bg: #ffffff;
    --link-color: #0f172a;
    --link-muted: #64748b;
    --link-hover-bg: #e2e8f0;
    --link-hover-border: #cbd5e1;
}

@media (prefers-color-scheme: dark) {
    :root {
        color-scheme: dark;
        --bg: #0b1220;
        --surface: #111827;
        --surface-strong: #161b2d;
        --text: #e2e8f0;
        --muted: #9ca3af;
        --border: #2f3a55;
        --shadow: rgba(0, 0, 0, 0.28);
        --card-shadow: rgba(0, 0, 0, 0.4);
        --link-bg: #111827;
        --link-color: #f8fafc;
        --link-muted: #94a3b8;
        --link-hover-bg: #1f293b;
        --link-hover-border: #374151;
    }
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding: 32px 16px;
    background: var(--bg);
    color: var(--text);
}

.container {
    width: min(960px, 100%);
    background: var(--surface);
    border-radius: 24px;
    box-shadow: 0 20px 60px var(--shadow);
    padding: 32px 36px;
}

header {
    margin-bottom: 28px;
}

h1 {
    margin: 0 0 10px;
    font-size: clamp(2rem, 3vw, 2.8rem);
    letter-spacing: -0.03em;
}

p {
    margin: 0;
    color: var(--muted);
    line-height: 1.75;
}

.grid {
    display: grid;
    gap: 24px;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    align-items: start;
}

.card {
    background: var(--surface-strong);
    border: 1px solid var(--border);
    border-radius: 18px;
    padding: 22px;
    transition: transform 0.18s ease, box-shadow 0.18s ease;
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: 0 18px 40px var(--card-shadow);
}

.card h2 {
    margin: 0 0 14px;
    font-size: 1.15rem;
    text-align: center;
}

.links {
    list-style: none;
    padding: 0;
    margin: 0;
    display: grid;
    gap: 6px;
}

.links a,
.links a.external-link {
    display: block;
    color: var(--link-color);
    text-decoration: none;
    text-align: center;
    padding: 2px 3px;
    border-radius: 6px;
    background: var(--link-bg);
    font-size: 0.92rem;
    border: 1px solid transparent;
    transition: background-color 0.18s ease, border-color 0.18s ease;
}

.links a:hover {
    background: var(--link-hover-bg);
    border-color: var(--link-hover-border);
}