*{
    margin: 0;
    padding: 0;
}
/* .banner_warp {
    margin-bottom: 28px;
} */
.banner img {
    display: block;
    width: 100%;
}
.banner_3{
    position: relative;
}
.download {
    display: block;
    width: 240px;
    height: 48px;
    background:url("../imgs/button.png") no-repeat center center; 
    position: absolute;
    top: 66%;
    left: 50%;
    margin-left: -26%;
    cursor: pointer;
}
.download:hover {
    background:url("../imgs/button-on.png") no-repeat center center; 
}