Viewer styles refactor

[mikemitchel]

The Viewer styles have complicated imports and seemingly circular dependencies that can often make it very difficult to figure out problems when a local style is being overwritten by a nested import. Need to break the styles down and move as much as possible local to the component that cares about that style, and make any top level or global styles easy to reason about and import as needed. For example, importing a single @variable requirement on even a simple .less file will often bring in extra styling as the first import starts grabbing it's dependencies that then grab their own dependencies inception style.