Adding X (close) buttons to mobile web surveys

The X button used to close a survey on a desktop web browser is not visible on a mobile web browser. To add the button to a mobile web browser, edit the CSS file as follows:

Important: It may be necessary to modify the size of the survey displayed. See Modifying survey sizes on mobile web for details.
.kpl-live-mobile > .neb-form-close-btn-container {
    display:contents !important;
    z-index: 99;
}