利用=>:after和:before实现
父元素=>position:relative
单线不需要倒角=>
:after{
content:'';
position:absolute;
100%;
height:1px;
transform:scaleY(0.5);
bottom:0px;left:0px;
orign-tansform:bottom left;
}
多线需要倒角=>
:after{
content:'';
position:absolute;
border:1px solid #000;
200%;
height:200%;
tansform:scale(0.5);
top:0px;
left:0px;
orign-transform:0 0;
}
多线需要倒角=>
:after{
content:'';
position:absolute;
border:1px solid #000;
tansform:scale(0.5);
top:-50%;left:-50%;
bottom:-50%;
right:-50%;
orign-transform:0 0;
}