Studio panel colors (again)

Hiya,
New with childthemes, but found and read this manual:
https://premium.wpmudev.org/wpmu-and-buddypress-themes/what-are-parent-and-child-themes/
and this thread:
https://premium.wpmudev.org/forums/topic/studio-theme-how-do-i-change-background-color-and-foreground-text-on-sliding-login-panel#post-57450

I must be missing something obvious, cause changing Stdio Theme BP-panel colors does not succeed. I did:
- install and activated child theme
- copied and adjusted studio/_inc/css/adminbar.css
- uploaded to studio-child/_inc/css/
No effect. Also:
- put my changes in studio-child/_inc/css/child.css
- uncommented @import url( _inc/css/child.css ); in studio-child/style.css
No effect.
O, and flushed browser cache numerous times, and tried Chrome to check.
No effect.
What am I missing?

Thanks in advance and kind regards,
Ronald