用after伪元素这样写可以吗？还是没听懂老师说的用before伪元素来设置的背景线是如何在景区按钮下面的。

*{

padding: 0;

margin: 0;

border: none;

}

html,

body{

height: 100%;

background: #93b3c6;

}

span {

display:block;

width: 16px;

height: 16px;

margin: 30px auto 40px;

border-radius: 50%;

background: #fff;

}

nav {

position: relative;

display: flex;

width: 78.125vw;

margin: 0 auto 45px;

justify-content: space-between;

}

nav:after/*before*/ {

position: absolute;

top: 12px;

width: 100%;

height: 10px;

background: #fff;

display: block;

content: '';

}

nav > a {

/*position: relative;*/

font-size:12px; padding: 10px; border: 2px solid #5935b4;

color: #255d7e;

text-decoration: none;

background: #fff;

z-index: 1;

}