This is very much a work in progress as I've only spent a couple of days with a live ISPConfig. I'm just seeing if this direction would interest anyone else and prompt me to push it to my Github account. Main points are the header at the top is position:fixed so it's always visible and the #submenu template has been slightly tweaked to provide for a nested dropdown menu. I'm not exactly sure where to put the #submenu but I like the idea of not taking up horizontal space and eventually make it look and behave more like a real desktop menu. All the buttons have a depressed hover state and the icon in the search bar is a Font-Awesome character so I'll add more of them to all the buttons a bit like Github.
No, just simple CSS tweaks. There are some great bootstrap widgets that would be nice to take advantage of but I'm not sure I want to depend so heavily on javascript for UI rendering. The Font-Awesome dependency alone is 300K but they are so easy to use, and they could replace megabytes of image based icons. The font can also be striped down to a minimum once the required icon set is determined. Here is another snapshot with a lighter top bar...
