[WIP] CSS Modules for console

[outoftime]

This is a proof-of-concept exploring what it would be like to migrate to CSS modules. In particular, it migrates all of the styles surrounding the console to CSS modules. The console is a good test area because it’s self-contained but still encompasses several components with various shared styles.

At this point my main takeaway is that I would like to try the same exercise with styled-components, as I felt that CSS modules have noticeable downsides. Sharing styles between different modules is awkward, as is introducing variants on base rulesets. At a higher level, the whole exercise of coming up with class names, applying them to elements, and then writing selectors with rulesets seems like overkill in a scenario when each selector is pretty clearly talking about a single element (or item in a collection of elements). I get the sense from reading its docs that styled-components addresses all of these pain points.

If we do move forward with CSS modules, though, this PR needs some work before merging:

• Use shared values rather than CSS variables
• Introduce the cssnext pipeline to get cross-browser compatibility
• Extract styles at build time
• Resolve ambiguity/awkwardness around expression vs. row
• Fix inactive console error specificity bug