IE8 Fixes (part 2)

Three small fixes here:

* #434 - CSS tweaks: Adding fallback colors for `rgba`, and swapping `::after` for `:after`
* #435 - Enable CORS support in jQuery
* #430 - Click event handler changes
Proper by modern standards, yes. But the alternate syntax is supported by everything.  As-is, these buttons just aren't showing up at all in IE8 because these aren't matching.  We could, alternately, refactor to not use :after at all here?