Fix #1214: Sphinx 4 <pre> overflow

[nienn]

This adds a max-width to the Sphinx 4 dl.property to prevent the overflowing of the pre tag that was occurring when placed inside this dl.

This specific dl class is set to display:inline-block, which doesn't deal very well with the white-space:pre from the pre tag. Adding a max-width to the dl.property should fix it.

Altered CSS

html.writer-html4 .rst-content dl:not(.docutils) .property, 
html.writer-html5 .rst-content dl[class]:not(.option-list):not(.field-list):not(.footnote):not(.glossary):not(.simple) .property {
  display: inline-block;
  padding-right: 8px;
  max-width: 100%;
}

Fixes #1214

[dp0s]

Thanks :)

[nienn]

Np. This will probably have to wait for the current release to move forward thought.

[agjohnson]

This looks like a good change to include in 1.0, our first release supporting Sphinx 4.

[agjohnson]

Easy enough! I don't think there is a test case for this in our docs either way, but didn't notice any significant changes with our test docs from this 👍