Ok so i’ve done i bit more of reserche and it appares that any time a modify any css line i need to restore a early version of those files, otherwise the display is wrong :
Files to restaure
located in : /web/wp-content/et-cache/4/
In fact it seems that the plugin W3 Total Cache are causing the issues. (The plugin was disabled).
I’ve tried to flush every cache with the plugin commande, even deleting manualy the cache on the server. But it’s keep causing trouble…