[galaxy-dev] How to customize Galaxy web interface?

Hi, I m running my own Galaxy instance and I would like to do some simple customization of the web interface such as adding my logos in the header frame, changing background colors, etc. I am having a look to static/ folders but I can't see clearly where the header frame is defined. Could you please tell me if there is any tutorial for doing so? Any starting point? Or which folder/file(s) corresponds to the web interface in the distribution? Best Regards, Pascal