[Theme: twenty fourteen] – responsive design – how to style menu?

Hey everybody,

I am having trouble with my site https://austrocult.si/. When viewed on a desktop computer, it looks fine. When you decrease window width or view it on a tablet, the secondary menu in the left sidebar gets pulled down below the page content, as it is supposed to do.

My problem is that the background color hover behavior on the menu items doesn’t work any longer once the menu changed its position, also the menu items take 100% width.

Where can I style the behavior of the menu once it is dropped below the content?

The additional CSS for the secondary menu in my child theme reads:

#secondary {
  background-color: transparent;
  border: 0 none;
  clear: none;
  float: left;
  margin: 0 0 0 -100%;
  min-height: 10vh;
  width: 122px;
}

Thank you all,

rich