I wanted to raise this again and see if we can find a solution. The CSS mismatch between the production docs site vs. local/preview builds complicates working on the docs. It’s not just color schemes: there are (visual) semantic differences between the two styles. Example below.
If there’s a licensing issue with the DSF owning the docs site styles, I’d think that could be solved somehow. (Do we know anyone at the DSF? 
) Maybe we could vendor the DSF’s CSS into Django’s docs with the DSF’s license intact, like we do for other vendored code (such as docs/_theme/djangodocs/static/fontawesome).
Here’s an example: we want to versionchanged:: two things related to the same function. There’s a bug in my reST source—can you spot it from the local docs build? (I didn’t.)
The mistake becomes visible on the production site: both of those paragraphs were meant to be inside the versionchanged:: directive, but only one is:
I ran into this particular issue in my own recent documentation work. But I’m guessing it’s not the only significant difference between the old and new docs CSS.
[Related aside: The bundled CSS on docs.djangoproject.com is missing a /*! license or copyright comment for DSF’s CSS, making it seem like it’s covered by FontAwesome’s MIT license statement from earlier in the bundle.]