How to hide "footer div" from pop-up

Site URL: https://www.flabelus.com

Hello everyone! Im getting a bit crazy on why this is not working. 

Im trying to hide the "Forgot password" and "Create user" div from the pop-up that appears when you try to access a member area as I dont want all users to be able to register.

I inspected the code and found is the following:

.uCx0nn2K5 footer {
    font-size: 12px;
    line-height: 44px;
    text-align: center;
}

So, i added the "display: none;" code in the custom css in my squarespace settings but when the pop-up is loaded again, it keeps appearing. 

Any idea or solution on how to " always hide" it?

Thanks in advance!

1) I first tried if it works in the code inspection panel, and it does

2) I added the code to the custom css from squarespace

3) I dont know why when page reloads still appears

Hi. It is in iframe tag, You can't hide it with code