A few months ago while working on a website I came across an annoying little issue; PNGs render differently in Internet Explorer and Firefox. The reason this is an issue is if you are trying to match the color of a PNG image with a CSS background color, if you design it for Firefox it will look wrong in Internet Explorer, vice versa.
After a bit of research I did come across a way to fix this issue, but before I get into that I will demonstrate the exact issue with the following four images: