Hardcoded hex value sweep

[brian-smith-tcril]

As mentioned in #351 (comment), there are some hardcoded hex colors in our stylesheets

Example:

frontend-component-header/src/studio-header/StudioHeader.scss

Line 37 in 8d46de8

border-right: 1px solid #E5E5E5;

It'd be good to go though, find those, and clean them up.