*{ margin:0;padding:0;box-sizing: border-box;}
.btn{
  display:block;
  width: 80px;
  height: 30px;
  text-align: center;
  line-height: 30px;
  position: relative;
  cursor: pointer;
  margin:100px auto;
}
.btn:after,
.btn:before{
  content:'';
  position: absolute;
  width: 100%;
  height: 100%;
  border: 2px solid #aea1a1;
  border-radius: 15px;
  top: -2px;
  left: -2px;
  z-index: -1;
  background: #eee;
}
.btn:after{
  z-index:-2;
  top:4px;
  background: #fff;
}