Remove white space above iframe

I've embedded a form on my website using the iframe code provided by JotForm. There's a pesky white space present on screens of certain sizes. I've attached a copy of the view from my desktop and my Android phone. Can you help me remove the blank space?

I've also attached something that appears to be helpful from Chrome's Inspector, but I don't know enough to know how to fix it.

Kindly use the following CSS code to adjust the margin spacing in your form.

.form-all {
    margin-top:-50px;
}

Use the designer to add the code and paste the code under the CSS tab.

Thank you!

Ah thank you! I've been searching for this for ages!