problem description before,after and other pseudo-elements and pseudo-classes have no effect the environmental background of the problems and what methods you have tried Project framework: iview + vue + stylus sets up the background system, and ca...
encounters a problem with first-child
multiple layers are nested with each other, and then use the p:first-child selector, which cannot be selected correctly. Code: <body> 111 222 333 < body> use p:first-child {color:red;} at this time,...
the problem encountered by the learning counter, the relevant information could not be found in two days of search. question 1: HTML: <div> text text text < div> CSS: div{counter-reset:pl;} p::before{content:counter(pl);c...