After several hours of work, we finally fixed a few bugs and flaws on this very website such as:
—the side bar: the categories appear at the top and the new “search” function
—the lightbox effect on posts with many pictures (try it of the previous post, for example. it is amzing!)
—several little graphic fine-tunings in the header and archive page for example
—possibility to move forward and backward when browsing posts alone

Thank you Jérôme!