IE not supported twenty twelve theme

Twenty Twelve works just fine in IE9.

Hello,
My website https://www.qb-quantobasta.net looks horrible on IE9, the menu is not centred and the images are with the original dimension and not the one I set.

How can I write some code to tell the website to adapt to tdifferent browsers?

@ersulla: It is impolite to interrupt another poster’s ongoing thread with a question of your own. You are not using the Twenty Twelve theme. Please post your own topic.