Theme color contrast issues

[phette23]

Andromeda pointed out the Philly theme has some contrast issues: https://wave.webaim.org/report#/https://2026.code4lib.org/

The primary red color and white do not have enough contrast. This happens in both the header main menu where we have white links on a red background and in the main body where we have red links on white background.

The fix would be to adjust some colors in the theme SCSS: assets/_scss/_variables.scss

We have a useful "theme" page which is good for checking color changes: https://2026.code4lib.org/theme.html (or running locally: localhost:4000/theme.html)

[phette23]

When the sponsorship PR is merged, also the links below the charts "Return to General Sponsorships", etc. are very hard to read as dark yellow on red background.