Not sure I really understand the question, but header tags have default padding. So if you want your header tag to have 0 padding, then you have to spec 0 padding. Also, when you do have something with a zero measure, don't use "px", "em", etc. Just put 0, e.g. padding: 0; - not padding: 0px;. It's not "wrong", per se. It will still work, but semantically, you don't use the measurements when something is just 0.