In ?__aural__=true mode all kind of crazy layout stuff can happen, but it's just for debugging.

In normal mode, we slap a bunch of CSS classes on this content which prevents it from affecting layout in any known browser or rendering scenario:

.aural-only {
  position: absolute !important;
  clip: rect(1px, 1px, 1px, 1px);

  /* NOTE: Without this, Safari sometimes lays these elements out at normal
     size. An example is the label on the comment action menu on timelines. */

  width: 0;
  height: 0;
  overflow: hidden;
}

This is consistent with recommendations from, e.g., WebAIM and generally standard practice.

It's possible that this ruleset isn't exhaustive and may require tuning at some point, but I don't anticipate any side effects in this case since I think it's a pretty standard one. We already make fairly regular use of aural-only and visual-only content without issues (you can access any page with ?__aural__=1 in the URL to have aural-only content shown in blue and visual-only content muted in transparent pink).