.ht-body {
    position: relative;
    min-height: calc(100vh - 105px);
}

span.fullscreen {
    width: 24px;
    height: 24px;
    position: absolute;
    top: 0;
    right: 15px;
    background-image: url(../images/fullscreen-sm2.png);
    background-size: contain;
    z-index:2;
    cursor:pointer;
}

    span.fullscreen.restore {
        background-image: url(../images/restore2.png);
        border: 1px ridge;
    }