Update documentation color scheme

[kafitzgerald]

PR Summary

Updates the documentation color scheme for more contrast using colors from the NSF NCAR brand standards.

Hopefully we can decide on something here that could then apply to all GeoCAT docs.

Alternately, we could take a look at this first on GeoCAT Applications or GeoCAT Examples since those have some additional visual elements.

[kafitzgerald]

Once we the link checker and pre-commit passing again I'm going get this updated.

I'm hoping we can decide on something here and apply it to the other GeoCAT branded projects or vice versa.

I was reminded of this by some color scheme issues on geocat-applications that would be nice to get fixed (e.g. with the highlighting on tables that's difficult to read).

[jukent]

Hi @kafitzgerald just checking in, since you asked for a review on this but it's marked as draft.

[kafitzgerald]

Ah, sorry for the confusion. I should have added a note as well when I marked this as draft.

I ended up doing something slightly different after discussing w/ Anissa and looking at GeoCAT-applications. I was planning to port that over to other packages at some point, but wanted to give it a bit of time to see how we liked it first.