@media screen and (max-width: 600px) {
    #kboard-default-document .kboard-document-navi .kboard-next-document {
        margin-top: 0 !important;
        width: 45% !important;
        float: right !important;
    }

    #kboard-default-document .kboard-document-navi .kboard-prev-document {
        width: 45% !important;
    }
}