css左右箭头
.record-left{
content: "";
width: 0;
height: 0;
float: left;
border-top: 10px solid transparent;
border-right: 10px solid red;
border-bottom: 10px solid transparent;
margin-top:5px;
}
.record-right{
content: "";
width: 0;
height: 0;
float: right;
border-top: 10px solid transparent;
border-left: 10px solid red;
border-bottom: 10px solid transparent;
margin-top:5px;
margin-right: 25px;
}