App-Layout addon, split vertical menu into header, menu and footer section

Hey everyone,

we are currently trying to tailor the App-Layout addon (version for Vaadin 11 / Flow) to our needs. What we specifically need is its vertical menu bar to be split into three sections (header, menu, footer) with only the menu bar area changing its height/introduce scrolling when the browser window changes height. We want the header and footer sections to be at a fixed position and always visible.

Judging from the source code, the respective web component used for the menu area is ‘app-drawer-layout’:
https://www.webcomponents.org/element/@polymer/app-layout/elements/app-drawer-layout

Source extract:

<app-drawer-layout>
  <app-drawer slot="drawer" align="end">
     drawer content
  </app-drawer>
  <div>
    main content
  </div>
</app-drawer-layout>

As far as we understand, ‘drawer content’ is the section that contains all the menu elements and currently has a global overflow behaviour for all contained elements. Is this correct? If yes, how can this be customized/replaced on the fly to our needs? Has anyone had the same problem with this addon maybe and already found a solution?

Any help is appreciated.

Thanks and best regards,
Mark