Revert "Improve callout shortcode. (#31802)" (#31871)

This reverts commit 5c6925385e.

site/content/docs/5.0/helpers/ratio.md

@@ -12,9 +12,9 @@ Use the ratio helper to manage the aspect ratios of external content like `<ifra
 
 Aspect ratios are declared in a Sass map and included in each class via CSS variable, which also allows [custom aspect ratios](#custom-ratios).
 
-{{% callout info %}}
+{{< callout info >}}
 **Pro-Tip!** You don't need `frameborder="0"` on your `<iframe>`s as we override that for you in [Reboot]({{< docsref "/content/reboot" >}}).
-{{% /callout %}}
+{{< /callout >}}
 
 ## Example