We are unable to change the background color of the iframe

None of these work for me. Trying to add the form to a Wordpress site. I can only change the frame to transparent (which doesn't show as transparent on the site). I can't change the background to transparent at all. Why is this such a difficult thing to do?

Based on what you have mentioned, the issue is with the iframe not changing its background color and you would need it to be transparent first.

To do that you could simply set your iframe with the following attribute and value: allowtransparency="true"

What that means is that you should change your current iframe from:

<iframe ...></iframe>

to

<iframe ... allowtransparency="true"></iframe>

Where ... represents all the other parameters that are already declared.