Password protect a single page

Hi,

Can anyone tell me where I can find the code to edit the ‘password protect page’ layout? The page I have password protected displays the text & login field in the top left corner which looks pretty tacky on a full width page.

Alternatively if there is a simply plugin where I can customise the login page I would live to know because every plugin I have found so far either protects the whole site or has an ugly login box.

Thanks