.collapse_span {

    position: absolute;

    bottom: 1px;

    left: 50%;

    width: 60px;

    height: 12px;

    cursor: pointer;

}

.collapse_span:before {

        content: "";

  position: absolute;

  top: 0; 

  right: 0; 

  bottom: 0; 

  left: 0;

  border: 1px solid rgba(12,131,242,0.5);

        transform: perspective(1em) rotateX(15deg);

    }

.collapse_span:after {

  content: '';

  position: absolute;

  bottom: 0;

  left: 50%;

  transform: translateX(-50%);

  border-left: 10px solid transparent;

  border-bottom: 6px solid #409EFF;

  border-top: 10px solid transparent;

  border-right: 10px solid transparent;

}

​

​