Fix Sidebar Active Element Highlighting

[vivekjain23]

When navigating through the documentation in the sidebar, it can be challenging to identify the current active element. The current styling for the active element is too similar to the rest of the tree. It would be helpful to make the active element stand out more clearly.

Suggested Improvements:

• Adjust the styling of the active element to make it more distinct (e.g., a stronger highlight, bold text, or a different background color).