How can I get thank you colors to match submission colors?

Want light gray, not default green. 

Just remove and replace the value of the form CSS under ".form-all" with:

.form-all {

background: #e7e7e7;

}

It should now replace the thank you page color with grey. Here's a sample screencast:

Let me know if you have any questions.

Hi, Jed.
Thanks for your help, which was great!
Is there a way to shorten the blue space? My form and thank you are small,
but the blue space extends down several inches below the screen real estate
I use. Might make it look cleaner.
Thanks,
Joe
...

Try re-embedding your form again using the code below.

[embed width="100%" height="450"]https://form.jotform.com/form/80096428537160[/embed]

https://www.jotform.com/help/299-How-to-Embed-a-Form-to-Wordpress-com

Let us know if you need further assistance.

Thanks, Marvih!
...