Styling the BB Editor

I am not very satisfied with the pale design of the BB editing window (e.g. colors of the elements in module /row/column settings etc.) so I am using the theme styles.css to correct some of the colors.

For example… .fl-builder-settings-section-header {background-color: #cdd4db;}

Is there any way to use some kind of BB plugin child css instead of main style.css?