Very noobish question

[Shagpile]

I have only just started using roundcube and all seems well.
However I am looking to over-customize it somewhat and am coming up against a couple of issues.

Is there any way to change the words username and password on the login screen to an image. The image I now have for a background stops the text being so legable so I want to replace it with a picture instead.

The second query I have is this;
if I use the domain mapping config to use only usernames without following domains, is there a way to for specific instances to use seperate domains. For example if username Benjamin is typed then it adds @bensemail.com to the end. If anything else is typed it adds @hilariesemail.com to the end.

I know these many be fairly basic questions but unfortunately while I can type HTML on paper with what people used to call a pen I am not very good (read rubbish) at CSS and scripting.

I hope you can help,
thank you,
Ben

[SKaero]

The best way to change the username/password text would be with CSS, its not that hard to learn I'd highly recommend it. The username tweak could easily be done with a plugin but that would require doing some php.