Formstack Form not embedding on SqaureSpace correctly

I put a code box on this page:

https://www.fhcmoms.org/application-new

 

and pasted this FORMSTACK form code in:  

 

<div id="iFrameWrapper"><div id="ffDialog"></div><div id="ffLookupDialog"></div><iframe frameborder="0" scrolling="no" name="ffEmbedFrame" id="ffEmbedFrame"></iframe><script type="text/javascript">function FFSetIframeSize(t,e){var n=document.getElementById("ffEmbedFrame");n.height=t,n.width=e}var i=document.getElementById("ffEmbedFrame");i=i.contentWindow?i.contentWindow:i.contentDocument.document?i.contentDocument.document:i.contentDocument,i.document.open(),i.document.write('<script type="text/javascript" id="jsFastForms" src="https://sfapi.formstack.io/FormEngine/Scripts/Main.js?d=mQE4mV_9F6iAsrmbKmk9F-0ICjHbfzbGm3-gCn6ekKKYigNqH-S4Ru_Du8aozyhy"></' + 'script>'),i.document.close();</script></div>

 

It displays as a narrow box and I can’t figure out how to change it to display the width of the page. 

 

I tried pasting this same code on a couple of other squarespace sites I manage and it does the same thing.