wp-auth-check uses full login page – possible to switch or customize?

i am using profile press lite to change the login page and have custom log in page that is working great, but issue arises when a logged in user gets logged out while viewing dashboard.

Since my login form is a separate page, it pops up the whole page in the wp-check-auth pop up, which is functional but not a good interface w/ all the extra page elements (header, footer etc). of the normal page

Is there any way to target the content in the iframe in order to remove it via css? ie, i tried: #wp-auth-check-frame #main-header #et-top-navigation {display: none;} to try and remove the navigation but that didn’t work. I am pretty sure that it’s not possible to target iframes w/ css… Is it possible to add custom css to the php page that generates the wp-auth-check pop up? I’m really just trying to remove the navigation (in header) while leaving the logo (in header) and remove the footer.

I know it’s a limited use case, but wondering how to make the pop up either the normal login page or at least customize it so i can hide some of the page contents such as header elements and the footer.

thanks!