How do I reduce the size of the background image on the Thank You Page?

Can you please try this HTML code for your Thank you page:

<div style="background: url(https://cdn.jotfor.ms/img/check-icon.png) no-repeat center center fixed;">
<h1 style="text-align: center;">Thank You!</h1>
<p style="text-align: center;">Your submission has been eceived.</p>
</div>

And use add this custom CSS

.thankyou{
background-size: cover !important;
}

Please give it a try and let us know if this fits your requirements.

Hi Richie, thanks for getting back to me. Unfortunately, it still doesn't work. Is it possible to just remove the background picture altogether?

Yes, you can remove the background picture, please follow this example:

Let us know if you need more help, we will be glad to assist you.

Please disregard my previous response, you are referring to the background in the Thank You page. To remove the background image on the Thank You page, please inject this CSS code in your form: https://www.jotform.com/help/117-How-to-Inject-Custom-CSS-Codes

body.thankyou{

background: none !important;

}