@tuanphan I have a business plan, but the code that you've outlined above doesn't work when I inject it in Page Settings > Advanced > Header. I'm not a developer, so I might be missing something, can you explain like I'm 5 years old?
This is the page I would like to change the color of: https://www.kelseyeaton.com/thank-you (no password needed)
I would like the background color to be #F6F6F6, do I just put that in place of "red" in your code?
Thank you!
EDIT: I do have a custom cursor, outlined in this forum post. Could that be causing the issue?