Fix layout for multiple blog entries. Adds max width.

src/layouts/RootLayout.astro

@@ -57,6 +57,7 @@ const { title = SITE_TITLE, description = SITE_DESCRIPTION } = Astro.props;
           "footer footer";
         grid-template-columns: 20rem 1fr;
         margin: 2rem 1rem;
+        max-width: 1600px;
       }
       .header {
         display: none;