Fix spacing issue with HTML4 images

[agjohnson]

This bug was introduced in #1185, it looks like the HTML4 selector
changed to not include directly descendents of .section elements.

I believe the issue was the missing > introduced here:
https://github.com/readthedocs/sphinx_rtd_theme/pull/1185/files#diff-2ad748ac9ebc515229907afab210e3bb370986d3db3a377f052ee5048dcc5b6cR36

But I'm also not familiar with the element that these rules are trying to target.

Fixes #1198

[agjohnson]

@Blendify it's not really clear what the fix in #1185 was addressing, so I'm not exactly sure what to test to verify this change. What was this selector supposed to target? Fix was easy, it seems just the direct descendant selector was missing.

[Blendify]

I am unsure exactly also, we really need to better organize and comment what styling goes to what markup

[agjohnson]

Heh yeah, seems we might have some investigation to do