Use this custom css, to add custom code you can check this documentation: https://www.joomshaper.com/documentation/helix-framework/custom-code-css-js-meta

div#spproperty .container .row {
    flex-direction: column;
}
div#spproperty .container .row .col-md-7.col-xs-12 {
    width: 100%;
}
div#spproperty .container .row .col-md-5.col-xs-12.spproperty-sidebar {
    width: 100%;
}

Thanks