Range sliders aren't styled properly in IE10–11

[gakimball]

IE10+ have support for styling native <input type="range"> elements in CSS, but the way we implemented it doesn't seem to be working, because all we get is this:

The slider still works, though.

One amusing quirk of custom range sliders in IE is that the paddle can't be taller than the bar itself. This is how our range sliders are currently styled, but there are likely weird border hacks we can use to get around it, and keep the look visually consistent with other platforms.