How to embed form into my website?

Hello, my website developer used the iframe option to embed one of my forms into my website. once embedded, the form doesn't look professional (half of the form is black) he advised me to contact you to solve the issue.

original form Link: https://form.myjotform.com/conventioneers/online-booking-form

Embedded form: https://www.conventioneers.us/cms/exhibitorbookingform.aspx

please advice, 

I checked the form link (https://form.myjotform.com/conventioneers/online-booking-form) you provided and it is working properly. After that, I checked the Page URL (https://www.conventioneers.us/cms/exhibitorbookingform.aspx) you provided and I was able to replicate the issue. 

As you mentioned on your post, you have embedded the form using the iFrame Method. Could you please embedding it again but this time use the default embed code? To do that, please follow this guide: https://www.jotform.com/help/34-Adding-a-Form-to-a-Web-Page

Please give it a try and let us know how it goes. Thank you.