:root {
  --bg: #f4f6f9;
  --panel-bg: #ffffff;
  --border: #d7dce3;
  --text: #1c2430;
  --muted: #6b7684;
  --accent: #2563eb;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12161c;
    --panel-bg: #1a2029;
    --border: #2b3340;
    --text: #e6eaf0;
    --muted: #93a0b0;
    --accent: #4d8dff;
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  min-height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", "Malgun Gothic", -apple-system, BlinkMacSystemFont, sans-serif;
}

.hub {
  max-width: 900px;
  margin: 0 auto;
  padding: 48px 24px 64px;
}

.hub h1 {
  font-size: 1.8rem;
  margin: 0 0 8px;
}

.lead {
  color: var(--muted);
  margin: 0 0 32px;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.card {
  display: block;
  background: var(--panel-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  text-decoration: none;
  color: var(--text);
  transition: transform 0.15s ease, border-color 0.15s ease;
}

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

.card-icon {
  font-size: 2rem;
  margin-bottom: 8px;
}

.card h2 {
  font-size: 1.1rem;
  margin: 0 0 8px;
  color: var(--accent);
}

.card p {
  font-size: 0.85rem;
  line-height: 1.5;
  color: var(--muted);
  margin: 0;
}