[MatthiasPortzel]

As a web developer, the things that bother me the most are the small differences in edge cases between the rendering engines.

What happens when you put a percentage height on a row in a table. What happens when an element has a margin that doesn’t fit in its parent. How does adding display: flex effect how text is laid out inside an element.

These are things that Gecko and WebKit/Blink handle differently. Some of them are defined in the spec and have tracking bugs, but some of them just aren’t addressed. I don’t think it’s maliciousness or laziness on anyone’s part, but the web is too complicated for there to be multiple perfectly compatible rendering engines.