input {
border : none;
display : inline-block;
width : 25px;
height : 25px;
-webkit-apearance : none; //去掉复选框的默认背景样式
}
.selected{
background : url(./img/selected.png) no-repeat;
background-size:25px;
}
.unselected{
background : url(./img/unselected.png) no-repeat;
background-size:25px;
}