The SideBar of our Demo application is implementing using the UI for ASP.NET AJAX TreeView control. With the help of @media queries we are determining whether the whole TreeView or a hamburger button will be shown. You can take a look at the exact impelmentation of the SideBar of our demo application by downloading the source code for the demos from your Telerik account.
In addition, I would advice that you also take a look at out RadPageLayout control and the ways to achieve responsive layout utilizing its functionality:
PageLayout Live Demo
I hope this information will be helpful for you.
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