Thanks for the tip, I'll be improving that in the patch releases soon.
Until that is done: It supports IE11, FF48+, Edge and Chrome. Mobile browser tests are on the way. Some things are ported from Normalize.css for backword compatibility, but the goal is to remove them as soon as IE11 drops below 1%.
In the future there might be a file version with IE11 and without IE11 support. IE11 is currently at 3,7% globally, so I still see considerable use there.
I meant that a lot of developers are now treating IE11 as the lowest supported version, so having it is a must. Having two branches (one without IE11) is probably the best.
Until that is done: It supports IE11, FF48+, Edge and Chrome. Mobile browser tests are on the way. Some things are ported from Normalize.css for backword compatibility, but the goal is to remove them as soon as IE11 drops below 1%.