How to make a sliding menu on content?

Question

css

There is an example of a site with a slidebar menu
blackrockdigital.github.io/startbootstrap-simple-s...
This example, with a small screen width, when opening the slidebar, expands the page and adds a scrollbar.

How to make the slidebar overlap the content from above and not move it?

Answer 1

Set the sidebar to absolute position and z-index