Fix #1190: Add classifier separation on html4 writer

[nienn]

This fixes #1190. The missing separator exists only as a CSS pseudo element. The selector that creates it is very specific and explicitly excludes the html4 output:

html.writer-html5 .rst-content dl dt span.classifier:before

Solution

Make the selector global:

span.classifier:before

Details

I made the selector global, instead of adding the specific selector container structure required for the html4 case, for two reasons:

• Did not find span.classifier being used anywhere else, in a different situation that would do badly with this styling.
  Might I be wrong here?
• I'm not sure about the html structure for the html4 writer.
  Ex1: html4 writer uses tables instead of dls (I did not test this thought)
  Ex2: v 0.5.2 does not add the class .writer-html5, even if it's using dls

[agjohnson]

In trying to explain some more test cases, I discovered the underlying issue: Sphinx 2 changed the structure of this classifier to match what is output by the HTML5 writer (this isn't specifically an HTML5 feature).

The Sphinx 1.x HTML4 output for the classifier actually had a hardcoded separator:

<dt>Term <span class="classifier-delimiter">:</span> <span class="classifier">classifier</span></dt>

Thinking about this more, perhaps the easiest solution is to always hide dl dt span.class-delimiter, just to keep our selectors more reasonable.

The fix in this PR currently will add an extra separator to Sphinx 1.x HTML4 output -- ie I'd expect Term : : classifier in the output

[nienn]

Added the dd dl to make the selector more specific. The .rst-content was also already present.
So now the proposed changes on that selector are just

from:

html.writer-html5 .rst-content dl dt span.classifier:before

to:

.rst-content dl dt span.classifier:before

Also added the rules to hide the hardcoded separator from Sphinx 1.x and prevent duplication of that element:

.rst-content dl dt span.classifier-delimiter {
	display: none !important;
}

[agjohnson]

Looks great!