.c1{
  width:400px;
  height: 200px;
  /* border: 1px solid red; */
  /* border:5px solid red; */
  /* border:5px dotted red; */
  border:5px dashed red;
}
.c2{
  width:400px;
  height: 200px;
  /* border-width: 30px; */
  border:30px solid transparent;
  border-image:url(https://gitee.com/SCD-Wear/img-bed/raw/master/css/border.png) 30 round;
}
.c3{
  width: 0px;
  height: 10px;
  border-bottom:30px solid red;
  /* border-right:30px solid blue; */
  border-left:30px solid transparent;
  border-right:30px solid transparent;
}