body {
    cursor: move;
}

.demo-viewport .center-page-part .demo-block {
    overflow: visible;
    /*border: 2px solid red;*/
}

.ball {
    /* center horizontally and vertically */
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 90px;
    height: 90px;
    border-radius: 50%;
    background: url("../images/ball.jpg") no-repeat;
    background-blend-mode: multiply;
    transition: 0.5s linear;
    z-index: 0;
}

.ontop {
    position: relative;
    z-index: 1;
}