Wave a11y report errors for material theme

[dmundra]

Wave is reporting a lot of errors for the material theme (currently 34 errors https://wave.webaim.org/report#/https://handbook.civicactions.com/en/latest/ and 8 contrast errors when using the browser tool).

To dos

• [x] Fix contrast errors in the "read the docs" popup that allows switching of branches.

Follow-up on the Wave a11y errors (see quote below from #926)

Looks like the a11y issues are known:

• https://github.com/squidfunk/mkdocs-material/issues/4006
• https://github.com/squidfunk/mkdocs-material/discussions/3156

For the keyboard navigation for sub-topics one option is enabling navigation sections and navigation expansion (https://squidfunk.github.io/mkdocs-material/setup/setting-up-navigation/#navigation-sections). We can also introduce tabs, if we overhaul the menu. Right now all top level pages would be tabs and that is a lot of tabs.

[ContentBrewmaster]

Fix accessibility issues with new theme

[dmundra]

Fix for contrast errors in #1004 and also the keyboard navigation for collapsed menu items is fixed the latest version (9.0.3).

[dmundra]

I believe the author will be fixing accessibility errors so as long as we keep our version up to date then we should get those fixes. I don't think wave errors will go down to 0 based on the architecture of the theme so for now closing this issue.