Improve contrast of footer

[kburk1997]

The contrast ratio of the footer text to the background is 2.19:1. This is well below the threshold for normal text under WCAG, and very difficult for users with low vision to read.

Level AA requires a contrast ratio of at least 4.5:1 for normal text, and Level AAA requires a contrast ratio of at least 7:1 for normal text.

Here is a contrast checker: https://webaim.org/resources/contrastchecker/