I changed the theme on the site. I used the Sleek theme from Studiopress.
The main reason to change to this theme was that I replaced some of my addons. For example, the breadcrumbs are already included in the theme. There is also an included widgets for Twitter.
Another reason is that I find this theme more good looking than the hold one. And finally, this new theme is more up-to-date.
I hope that you will find this theme adapted.
I've still some work to do adapting this theme for the site. If you encounter any kind of problems with the new design, don't hesitate to let a comment or to contact me.