Resizing background image for Promo pop-up on mobile

Site URL: https://www.urbanvoguedayspa.com.au/

Hi, hoping someone can help ASAP, my background image is cropping super small for my mobile promo pop-up, below is the code I've used to get the image to show up on mobile: 

.sqs-slide-wrapper[data-slide-type="popup-overlay"] .sqs-slide-container[data-slide-type="popup-overlay"].overlay-mobile-styles-enabled .group-copy {
    background: url("https://static1.squarespace.com/static/5afbefefe17ba3b4ea798071/t/5fd88b6aeaa8e77ae8edeecb/1608026989540/lime-and-coconut-urban-retreat-urban-vogue.jpg");
  }
}

Hi. Do you still need help on this?

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I don't see promotional popup..