Improve accessibility: no JS *required*! (at least while navigating the site)
Please change the concept of navigation radically. To create sites nowadays, which are not accessible because of a JS-driven menu system is a bad practice for sure.
You even cannot set a bookmark whithin the next generation panel... And you cannot always choose to activate JS (Internet Cafés, corporation networks).
Moreover this way ISPConfig ist not accessible by command line browsers. And this may be a reason for Hetzner why to have not choosen ISPconfig. (You can browse SysCP at the command line and I guess, the guys at Hetzner appreciate it.)
To upload designs, you'll need to enable LFS. More information