Responsive sidebar Toggle Menu Push content on click in ASP.Net

I tried to fix the side bar and make it un scrollable, when I applied the code the side bar did not move when the page content was scrolled, but it made the side bar to cover part of the content (left side of the content), which was unable to see and use the span button. However I want the side bar to appear the way it is in the second image and still be un scrollable.