.gf-slider-box {
    position: fixed;
    height: 100%;
    display: table;
    vertical-align: middle;
    top: 0px;
    z-index: 1000;
}

.gf-slider-box-content {
    position: relative;
    display: table-cell;
    vertical-align: middle;
    overflow: hidden;
}

.gf-slider-button {
    position: absolute;
}