Given a transparent PNG displaying a simple shape in white, is it possible to somehow change the color of this through CSS? Some kind of overlay or what not?
There's no need for a whole font set if you only need one icon, plus I feel it being more "clean" as an individual element. So, for this purpose, in HTML5 you can place a SVG directly inside the document flow. Then you can define a class in your .CSS stylesheet and access its background color with the fill
property:
Working fiddle: http://jsfiddle.net/qmsj0ez1/
Note that, in the example, I've used :hover
to illustrate the behaviour; if you just want to change color for the "normal" state, you should remove the pseudoclass.