Select Clean theme. With editing on in Home page ADD a login block. Turn editing off and log out. With the front page still open, TEST that the Login block, 'username' and 'password', input boxes do not overhang into the gutter between side blocks and main content (side-pre), or side blocks and page edge (side-post). Continue testing when resizing screen on desktop, also test on mobile devices, tablet, laptop etc...if possible. TEST for regressions (there should be none) using an RTL language, like Hebrew (he) for example.