Improve CSS for API documentation

[choldgraf]

In executablebooks/meta#286 @rscohn2 noticed that our CSS for API docs looks a bit wonky. @chrisjsewell pointed out that the CSS for this is here:

sphinx-book-theme/src/scss/_page.scss

Lines 232 to 234 in bdcf106

	// auto-doc, see: https://www.sphinx-doc.org/en/master/usage/extensions/autodoc.html#directive-autoattribute
	// adapted from https://github.com/readthedocs/readthedocs.org/blob/master/readthedocs/core/static/core/css/theme.css
	dl.module, dl.class, dl.exception, dl.function, dl.decorator, dl.data, dl.method, dl.attribute {

so we should fix up the CSS there so that this type of API docs looks good!

[rscohn2]

I only have basic knowledge of CSS, but if someone could suggest what properties need to change I would like to try to fix this.

[pradyunsg]

Do you have examples of this wonky looking pages?

I'm looking at https://sphinx-themes.org/sample-sites/sphinx-book-theme/demo/api.html, and it seems OK to me on mobile.

[rscohn2]

The main problem seems to be the lack of spacing between the type and the identifier. I put a simple example and screenshot at executablebooks/meta#286
I see 'intsz' but it should be 'int sz'

I see the same problem looking at the C++ examples at:
https://sphinx-themes.org/sample-sites/sphinx-book-theme/demo/api.html#c-api

and I have many examples at:
https://oneapi-src.github.io/oneAPI-spec/elements/oneDNN/source/primitives/logsoftmax.html

[rscohn2]

I added a custom.css with the following contents to fix the problem. Not sure if this is appropriate as a general fix.

/* A workaround for https://github.com/readthedocs/sphinx_rtd_theme/issues/647
 * Override display for function signatures so that there is spacing between
 * types and arguments */
dt {
    display: table-cell !important;
}

[rscohn2]

Thanks for fixing it.