Gruvbox Dark Medium selection background is difficult to see

[manuelpoelzl]

The theme is really great and pleasant to use, but there is one thing that could be improved.

The background of a selected item is very difficult to see in the menu, you have to look very closely to see what exactly was selected.

As you can see in the screenshot, the color combo is not the most advantageous, maybe you could adjust that to make it more obvious