使用css3创建具有css箭头的框

.box {
  position: relative;
  margin: 18px;
  width: 8em;
  height: 6em;
  border: 1px solid rgb(77, 77, 77);
  color: #FF1919;
  background-color: pink;
}
.box:hover {
  width: 8em;
  margin: 18px;
}
.box:before {
  content: '';
  position: relative;
  width: 30%;
  left: 18px;
  right: 80%;
  height: 40px;
  top: 30%;
  background: rgba(0, 0, 0, 0.1);
  display: inline-block;
  background-color: blue;
}
.box:after {
  content: '';
  position: absolute;
  left: 43%;
  top: 30%;
  margin-top: -18px;
  border-style: solid;
  border-width: 40px;
  border-color: transparent transparent transparent rgba(0, 0, 0, 0.1);
}.box {
  position: relative;
  marg