For illustration puposes  I created a web page with these workds, one on each line

every

good

boy

does 

fine

When I insert the iframe between "boy" and "does", about 8 extra blank lines are added on the bottom.

https://themezz.com/zoho/  shows the issue.

(I want to use the frame code on a wordpress self-hosted web site and I do not want the added blabk spaces at the end)

Any ideas?