Accessibility and Compliance Changes

[mroley1]

Things addressed in this PR

• tab navigation => Some interactable elements were not included in the tab order for the site. Additionally, there were some elements what did not visually change when they are focused. Most of these are fixed in this pr (see note).
• prefers-reduced-motion and prefers-reduced-transparency media queries => these are for individuals who are made sick by looking at continuous motion or have a hard time reading text on transparent backgrounds. There may be some enhancements that can be made to this coverage, but the glaring issues are fixed in this PR.
• screen reader changes => some elements such as the categories and sponsors were not accessible to screen readers.

NOTE: I kept the spirit and structure of most of the elements I touched with one exception. When adding visual markers to the sponsors section instead of going for a boring box I tried to be cute with it. Check out the changes to the animation and see if that is something you are interested in. I can rework it to be something more traditional if you would rather.

ADDITIONALLY: I still have concerns about color contrast in some areas and the accessibility of the FAQ section. These are not addressed in this PR

[kaclark219]

Thank you for your help! I was able to implement a lot of your changes into our current live site, but because the codebase uses SCSS instead of base CSS for styling, I had to manually add in a lot of the style edits & let it remap. For the sponsors, I ended up editing it a bit to remove the lift (felt a bit jarring) & having the visual shadow only appear on the sponsors that are actually clickable. Also, I'm still (almost constantly) working on the FAQ section to improve it overall, so that'll probably still be a work in progress over the next few months.

p.s. i'll do some color checking to find any areas that don't pass aa standards at least

[kaclark219]

p.p.s. everything but the scrolled (semi-transparent) nav bar passes color contrast checking! i also fixed a couple other WCAG 2.0 A things that i'll be pushing tonight