.app_sec{
    padding: 3em 0 5em;
    position:relative;
    width:100%;
    height:100%;
    bottom:0px;

}
.app_sec:after{
    content:'';
    position: absolute;
    left: 0;
    bottom: 0;
    height: 100%;
    width: 100%;
    background:url('../images/gallery-bg.svg') no-repeat;
    background-size: 100%;
    background-position: bottom center;
}