Set variables for all styles

[Jaeiya]

There is a lot of CSS that has been created without any variable considerations. The whole point of having a single source of truth for all colors, is that we can easily change colors across the site with often-times a single variable. Right now, there's a lot of colors which are not set up as variables; this was due to necessity, since our priority right now is to create new functionality and stabilize existing functionality.

All CSS colors need to be assigned to variables.ts so that we can more easily maintain the palette of our site.

[Jaeiya]

This is a very trivial but tedious issue so I'm moving it to the next milestone.