About Changing Default UI of Frappe

Hey, I wanted to have a custom colors for the desk, so i was trying some combinations, mostly background colors. I changed the colors inside the code at path: frappe-bench/sites/assets/frappe/dist/css/desk.bundle.YBH6RMPH.css.
but after the bench was stopped and started all my changes were gone. How to avoid this.

From this to

I was back at to default white bg!

I assume this will be helpful to you. Check this