[examples/openspending][xl]: add table preview to showcase page, minor fixes (#895)

Co-authored-by: deme <joaommdemenech@gmail.com>

examples/openspending/components/_shared/Layout.tsx

@@ -2,7 +2,7 @@ import { Header } from '../Header';
 
 export default function Layout({ children }) {
   return (
-    <div className="bg-white min-h-screen">
+    <div className="bg-white min-h-screen pb-32">
       <Header />
       {children}
     </div>