Ok, I fixed this by myself.
Perhaps it′s of any help to somebody, so here′s the code:
.gt_switcher_wrapper {top: 9.2em!important; color: white!important; background-color: black; border: 0px solid red; padding-left: 5px; padding-top: 2px; padding-bottom: 2px; !important; /* changes the wrapper */}
.gt_switcher_wrapper a.glink {color: white!important /* Link in the wrapper to white */ }
.gt_white_content a.glink {color: black!important /* in the pop-up window all links=languages to black */}
.menu-item-gtranslate {background-color: lightgrey!important; color: black!important; /* in Show in Menu change the background */}
.menu-item-gtranslate a.glink {color: black!important; /* in Show in Menu change the link color */}
Have a nice day