Use an SVG icon, this one comes from Iconic. Icon melon is also good
Otherwise you could use a font-icon, this one comes from FontAwesome
If you must, you can use a CSS Filter but it is only supported in newer browsers. The best fallback would be to use SVG filter to do the same thing and use a data URL to apply it. Demo
-webkit-filter: invert(100%);
You could also use a sprite like agconti suggested
