Vertical toolbar menu is broken in narrow viewports

Problem/Motivation

When you got the admin menu blocked on the side of your screen,
And you resize your screen to mobile device width the white bar below the menu disapear so you can see your content what is nice. but you cant click anything below your menu becaus of a wrapper wich is full screen. so you can see your fields but you cant edit them until you close your menu.

I dont know if this is a problem.
People doesnt resize there screens many times, and if you open your menu you want to navigate not to look and continue editing your content.

Proposed resolution

i think the solution is to change this css class on mobile:
remove the bottom 0 property.

.toolbar-oriented .toolbar-tray-vertical > .toolbar-lining:before {
/* bottom: 0; */
}

Remaining tasks

* change the css of the menu-toolbar and create a patch
* test the patch