org-theme/scss/partials/_nagivation.scss

#org-div-home-and-up {
    position: absolute;
    right: 0;
    z-index: 100;
    padding: 10px;

    // Large Screens
    @media all and (min-width: $content-max-width+$toc-width) {
        right: auto;
        width: $content-max-width+$toc-width;
        text-align: right;
    }

    // Small screens
    @media screen and (max-width: 768px) {
        position: fixed;
        padding: 1em;
        color: $color-primary-background;
        a {
          color: $color-text-invert;
        }
    }
}