Use `calc()` to improve precision

Fix gh-8
0.6.1
Add 'files' to package.json

Fix gh-14
Remove MQ files from component.json

Component(1) has no good way to support this use case; needs tooling.
Therefore, this is blocked by: https://github.com/suitcss/suit/issues/51

Fix gh-15
0.6.2
Merge branch 'master' into gh-pages
Update build