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I checked your website but I can't view it on my end, this is how it looks like:
Have you tried embedding the form using the iFrame embed code? It is also possible that you might need to adjust the actual responsive settings or styling in your Zara.
To make the JotForm forms mobile responsive, you can check this guide: https://www.jotform.com/help/322-How-to-make-mobile-friendly-forms-on-JotForm
I hope that helps.