Empty :root blocks are being output in CSS

[erikjung]

Because of block comments within :root blocks, our CSS output has many instances of:

:root {
}

We should think about:

• Changing how :root blocks are commented (perhaps doing away with the /* n */ annotations)
• Implementing https://github.com/ben-eb/postcss-discard-comments as well

[tylersticka]

Would this be resolved by optimization tasks when we get to the point where we're building production CSS files?

[erikjung]

I bet the comment removal would, but I'm not sure about the empty blocks. Though, I still think it's worth it to have these quirks cleaned up in our working output to make it easier to look at during development.

[erikjung]

Closed via #81