div#hierarchy-div-box {
    position : fixed;
    top : 0.5em;
}
/* inside the box */
div#hierarchy-div {
    position : relative;
}
div#up-div-box {
    position : fixed;
    top : 0.5em;
    right : 0.5em;
}
/* inside the third cell */
div#up-div {
    position : relative;
}
/* div to go to previous image */
div#prev-div {
    position: fixed; 
    left: 0.5em;
    top: 3.5em;
    font-size : large;
    margin : 0.5em;
}
/* div to go to next image */
div#next-div {
    position: fixed; 
    right: 0.5em;
    top: 3.5em;
    font-size : large;
    margin : 0.5em;
}
/* title of the image */
div#title-div {
    text-align : center;
    font-size : large;
}
div#credit-div {
    color : grey;
    text-align: right;
    margin : 0.5em;
}