Sidebar content overflows on mobile devices

The sidebar height overflows on mobile due to the browser's (like chrome) address bar is visible, causing `100vh` height to change dynamically.
Steps to reproduce:

- Open amfoss.in on a browser with dynamic address bar visibility (like chrome)
- Scroll and make sure the address bar is visible
- Open the sidebar

Possible fix:

- using `dvh` instead of `vh`