核心提示：伪类before和after .one {font-size: 50px;color: red;}.one::before {/*content必须填写，有没有值无所谓*/content: ;colo...
伪类before和after
.one {
font-size: 50px;
color: red;
}
.one::before {
/*content必须填写，有没有值无所谓*/
content: "";
color: green;
}
.one::after{
content: "after";
color: purple;
}
伪类
清除浮动
.clearfix::before,
.clearfix::after {
content: "";
clear: both;
display: block;
}
