Beautify Desk GUI

Hi, I am using ERPNext: v13.20.0 (version-13)
I want to change Desk GUI. I checked by installing redtheme, whitetheme app from following urls:

Is there any other way to beautify Desk Interface like by css files etc ?

Yep, you can inject any css you want:

https://frappeframework.com/docs/v13/user/en/python-api/hooks#desk

Thank you so much.