Make enabling/disabling of mode more obvious

[UJehle]

Is your feature request related to a problem? Please describe. I just tested the new version. First, it looks great! And I like the isochrone feature with the different transport modes a lot. Just one thing that is a bit unclear to me: Which modes are choosen here? Does dark grey means "enabled" or "disabled"?

Describe the solution you'd like Maybe it helps to have a description when hovering over the mode, saying "enable" / "disable".