:root {
  --bg: #f9fafb;
  --card: #ffffff;
  --text: #111827;
  --muted: #6b7280;
  --border: #e5e7eb;
  --accent: #2563eb;
}
* { box-sizing: border-box; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  margin: 0;
}
.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 1.5rem;
}
nav.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}
nav.nav a {
  text-decoration: none;
  color: var(--text);
  padding: 0.5rem 0.75rem;
  border-radius: 6px;
  border: 1px solid transparent;
}
nav.nav a:hover, nav.nav a.active {
  border-color: var(--accent);
  background: #eff6ff;
}
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.25rem;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}
.footer {
  margin-top: 2rem;
  color: var(--muted);
  font-size: 0.9rem;
}
.iframe-wrap {
  position: relative;
  width: 100%;
  padding-top: 62.5%;
  background: #f3f4f6;
  border-radius: 8px;
  overflow: hidden;
}
.iframe-wrap iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}