.ui-dialog {
    max-height: calc(100% - 100px);
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    z-index: 10001 !important;
}

.toolbar-tray-open.toolbar-horizontal .webform-modal{
    transform: translate(-5%, -5%);
}

.webform-ui-dialog {
    transform: none;
}