Passwordless Lock CSS question and Email white listing

Hi, I have managed to set up the passwordless custom HTML log in, and I can change colours and logo. But is there any CSS rules available so I can add a background image to the page and move the log in box to the right of the screen?
I only know CSS and HTML so not sure is this at all possible?

Also I implemented the rule to whitelist only certain domains to be able to register and log in. Works great. But is someone with a none white listed domain tries to register they get a code and when they enter the code they are told access denied. Is there a way to stop the code being sent and show an alert access denied before the code is sent?

Many thanks in advance