<div style="display:grid;gap:12px">
<.container><div class="ui-layout-demo">Container, 1200px</div></.container>
<.container size="narrow"><div class="ui-layout-demo">Narrow, 720px</div></.container>
<.container size="prose"><div class="ui-layout-demo">Prose, 640px</div></.container>
</div>