html示例 一开始这样写不生效
<div> <span>示例代码</span> </div>
span{
content:"";
width: 89px;
height: 2px;
background: #02B7CA;
border: 2px solid #02B7CA;
}伪元素添加display:inline-block;
span{
content:"";
display: inline-block;
width: 89px;
height: 2px;
background: #02B7CA;
border: 2px solid #02B7CA;
}2.元素使用相对定位，伪元素使用绝对定位
div{
position: relative;
}
span{
content:"";
position: absolute;
width: 89px;
height: 2px;
background: #02B7CA;
border: 2px solid #02B7CA;
} 
