how to change the width of the side panel

Hi,

The width of the side panel is set by css (http://umap.openstreetmap.fr/static/CACHE/css/output.cf8c34d27c07.css), value 400px.

Unfortunetaly it’s too wide and I would like to set it to 200px (or at least ‘auto’).
You can see it here http://umap.openstreetmap.fr/fr/map/indigonails-collaborateurs_614177.

Do you think there i sa way to solve that?
Best regards
Denis