子衿沉夜
如果只是视觉上的这种效果，小面一个小的div有2个虚线边框在旋转45度绝对定位到那个大的虚线DIV上即可如：.d1{position: relative;
border: 1px dashed #999;
background: #fff;
width: 150px;
height: 100px;}.d1 span{display: block;
width: 20px;
height: 20px;
position: absolute;
border-right:1px dashed #999;
border-bottom:1px dashed #999;
transform: rotate(45deg);
bottom: -10px;
left: 50%;
margin-left:-15px;
background: #fff;z-index: 99;}