.Opm-states-hidden {
    /* http://snook.ca/archives/html_and_css/hiding-content-for-accessibility */
    border: 0;
    clip: rect(0 0 0 0);
    height: 1px;
    margin: -1px;
    overflow: hidden;
    padding: 0;
    position: absolute;
    width: 1px;
}