only supported fully in version 7). Internet Explorer's lack of support for PNG images has been debated, as many web developers wanted to move away from the old GIF format, which does not have the same capabilities and image quality as PNG.

Mozilla had implemented most of CSS Level 2 and some of the not-yet-completed CSS Level 3 standard. It was among the first browsers to pass the original , although it doesn't fully pass the more rigorous Acid2 test for HTML,