Danke hat dfunktioniert!

Marco, i posted here your replay by email, so that Frank could know it's ok!
Thanks to reply on the forum

Thank you @frago to have helped Marco! (i really like it when user help each other!)

Just to mention (as Google Translation not very clear...) that you don't need to edit files to add custom css, as you can use iCagenda option for that.
This one is in Global Options of component > General Settings > at the bottom of this page (the place of this option may change in the future, but will still be there as it is really useful to change just a few things. And for info, later it's planned in my (very) long todo list, to refactory the button, and add options for display But today, the CSS trick works great!)

Thank you all!
Best Regards,
Cyril