The problem when adding 0.5 px pixel border pseudo-class to the vue project

when writing the vue list, because we want to add the border of 0.5px, we can only use pseudo-class, but the pseudo-class is added to the parent element, but on the web page, the child element adds pseudo-class, and the parent element has no pseudo-class. I think it"s strange, is it the life cycle of vue?

clipboard.png

clipboard.png

Mar.23,2021

you are equivalent to writing ul li *: before , it should be ul li:before


can not leave spaces, directly ul li:before

Menu