Making changes to websites is tricky, because even small changes may lead to visual regressions in the page layout. For example, changing a bit of CSS to fix something somewhere may blow up in a completely different place. I could just click around and make sure everything looks okay, but that is boring and error-prone. What if I told you that there is a way to make sure that every pixel on your site is perfect, staying just they way you intended it to be?
