Breadcrumb issue (hidden only for posts when large screen is used)

Hi,

My site is responsive. I've got a problem with my breadcrumb. It's hidden when you see a post if you use a large screen. Have a look at this post:
http://creersonsite.net/lancement-creer-son-site/

Problem is only here on posts, not on pages. On a page, it works ok whether you use a sidebar or not. So I guess it's related to the way my theme deals with preset menus but if you have any idea that can help me... :wink:

Best Regards