html,
body {
    position: relative;
    height: 100%;
}
.prolunbo{
    /* width: ; */
    position: relative;
}
.prolunbo .arrow-left {
    background: url(../img/productleft.png) no-repeat center;
    position: absolute;
    /* background-size: 100% 100%; */
    left: 0px;
    top: 50%;
    margin-top: -15px;
    width: 50px;
    height: 55px;
}
.prolunbo .arrow-right {
background: url(../img/productright.png) no-repeat center;
position: absolute;
/* background-size: 100% 100%; */
right: -10px;
top: 50%;
margin-top: -15px;
width: 50px;
height: 55px;
}