Hello,

The size of the popup on the regular page comes from the “Popup width” field that is situated in Theme Settings -> General -> Promo popup and also has the default value of the width is 800px.

https://gyazo.com/13dd52020766a8341caffa5f133decc5

In your case, the width of the “Popup” element is not defined so you should set the width and save it.

https://monosnap.com/file/v22al9Mxv6nLd7Lx9iXzqAfLBt1Y5v

If you have other concerns or additional questions, please get in touch.

Kind Regards