`<aside>` needs to be more recognizable as such (CSS)

[cabo]

The RFC editor CSS for <aside> has a quite distinctive layout (well, except that it is the same as for <blockquote>, which is a bug on its own). The special layout for i-d-template is not nearly as distinctive, except that it renders the whole aside in italics. This has already led to comments from reviewers who didn't understand that [such an aside][] is not semantically part of the main body of the text, i.e., in RFC 7991 terms:

2.6.  <aside>

   This element is a container for content that is semantically less
   important or tangential to the content that surrounds it.