body { margin: 0; font-family: system-ui, -apple-system, "Segoe UI", Arial; }
.topbar {
  position: sticky; top: 0;
  background: #fff; border-bottom: 1px solid #eee;
  padding: 12px; display: flex; gap: 8px;
}
.content { padding: 16px; }
.spacer { height: 900px; }
section { border: 1px solid #ddd; border-radius: 10px; padding: 16px; background: #fafafa; }
button { padding: 8px 12px; border-radius: 8px; border: 1px solid #ccc; background: #fff; }
button:hover { background: #f3f3f3; cursor: pointer; }