#shadowbox_nav_previous a {
    position: fixed;
    left: 5px;
    top: 48%;
    font-size: 200px;
    opacity: 0.1;
}

#shadowbox_nav_next a {
    position: fixed;
    right: 5px;
    top: 48%;
    font-size: 200px;
    opacity: 0.1;
}