The id used in the HTML is nav-bar, not navbar your selector needs to match.
Your
#nav-barshould always be at the top of the viewport.
In case you need help with the code formatting.
When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.
You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.
See this post to find the backtick on your keyboard.
Note: Backticks (`) are not single quotes (').