Accessibility: Insufficient color contrast of some elements

[dgodongm]

Text on numerous buttons and a paragraph element have insufficient color contrast against their background.

Repro Steps:

1. Navigate to https://joinmastodon.org/
2. Run Axe DevTools or other A11Y tools

Results: 9 elements flagged as having insufficient color contrast: 8 buttons which are only slightly below WCAG 2 AA 4.5:1 guidance at 4.37:1; and a

element with text that only has 2.77:1

Expected Results: All elements should meet WCAG 2 AA guidance on color contrast to better ensure content is accessible

[dgodongm]

Similar/same issues occur throughout https://joinmastodon.org/ pages

[dgodongm]

Seems addressing this may be challenging given Mastodon's branding colors.