title: purecss.io Grid Breaking in Firefox
body: <p>I've noticed that in purecss.io Firefox grids don't work unless I set display=flex for each grid that I want to horizontally align and then stack in responsive. If I don't want them horizontal and to always stack (e.g. two pure-u-1 boxes on top of each other) then I can't use display=flex. However, using this breaks compatibility with IE8. Does anyone know how to fix it so purecss works for Firefox?</p>