左尖角：
image.png
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<style>
*{
margin:0;
padding:0;
}
.box{
position: relative;
width:500px;
height: 100px;
background: #fff;
border:1px solid #d2d2d2;
margin:100px;
background-color: #f6f6f6;
}
.trag{
width: 0;
height: 0;
border-width: 9px;
border-color:transparent;
overflow: hidden;
position: absolute;
}
.trag1{
border-style: dashed solid dashed dashed;
}
.trag2{
border-style:dashed dashed solid dashed;
}
.trag3{
border-style: dashed dashed solid dashed;
}
.trag4{
border-style:solid dashed dashed dashed;
}
.trag-right{
border-right-color: #d2d2d2;
top: 30px;
left: -19px;
}
.trag-left{
border-right-color: #f6f6f6;
top: 30px;
left: -18px;
}
.trag-top{
border-bottom-color: #d2d2d2;
top: -18px;
left: 300px;
}
.trag-btm{
border-bottom-color: #f6f6f6;
top: -17px;
left: 300px;
}
.trag-right2{
border-left-color: #d2d2d2;
top: 30px;
left: 500px;
}
.trag-left2{
border-left-color: #f6f6f6;
top: 30px;
left: 499px;
}
.trag-top2{
border-top-color: #d2d2d2;
top: 100px;
left: 300px;
}
.trag-btm2{
border-top-color: #f6f6f6;
top: 99px;
left: 300px;
}
</style>
<body>
<div class="box box1">
<div class="trag trag1 trag-right"></div>
<div class="trag trag1 trag-left"></div>
</div>
<div class="box box2">
<div class="trag trag2 trag-top"></div>
<div class="trag trag2 trag-btm"></div>
</div>
<div class="box box3">
<div class="trag trag3 trag-right2"></div>
<div class="trag trag3 trag-left2"></div>
</div>
<div class="box box4">
<div class="trag trag4 trag-top2"></div>
<div class="trag trag4 trag-btm2"></div>
</div>
</body>
</html>
