Some glaring cross browser issue fixes

[stuartsan]

• there was a critical flexbox layout issue in firefox
• basically nothing worked in ie because it needed a couple polyfills
• there were a couple critical flexbox layout issues in ie

TODO

• there is still one glaring issue in ie, you guessed it, having to do with flexbox:

possibly will add that on to this PR or might split out depending on timing.

[cbcowans]

flex in css is not something I'm super experienced with but it all makes sense to me! 👍

[shazow]

:+1: also

[stuartsan]

Doin it! Thanks