Enterprise: Allow for separate icon on login page and admin interface (along with CSS)

[TheThing]

I think it would be nice if we could have separate logo for the login page and admin page.

Currently the login page has no CSS limit on size which allows my circular logo to look nice and shiney:

However in the admin interface, the same logo is limited to only 25px height which makes it look really weird:

It would be nice to be able to

a) have separate logo between the admin and login page
and/or
b) customize the CSS for the admin logo

If we could be given ability to inject CSS I could do something like this:

.hs-overlay .px-8 img {
  height: 100px !important;
  margin: 0 auto;
}

and it would look perfect