border-radius and background-image (+ a few other bug fixes)

- use border-radius (with "inset" shadow!) around rows in index, forum, topic and post pages.

- a fixed #footer

- use background images

- a few other bug fixes (like 12e5404e980f87e7490889d57f2d74a8af2cb267, 1d693d961dd55a59519977be1fd4bdd82b73e45f and 299d6050a1070d9db8486542bc32b1fc78713aea)