Why two colors for menu items?

Hello,

I do not know whether it is a bug or feature because I did not read source code.

In menu two colors are used for items, see attached screenshot.

One color is directly bg_color and the second is from schema ".view row:nth-child":

.view row:nth-child(odd):not(:selected) {
background-color: shade (@base_color, 0.6);
}

Why?

Thanks, Reg.

Seems like a bug to me. What theme are you using?