Visual diff: huge UI on Material for MkDocs

[humitos]

Example found in https://prairielearn--11830.org.readthedocs.build/en/11830/question/index.html?readthedocs-diff=true

[humitos]

I just realized that we don't have CSS variables for docdiff.css file, so we will need to add them first: https://github.com/readthedocs/addons/blob/main/src/docdiff.css