Binaya I have made the recent change to the child CSS per your recent recommendation – however when the menu is toggled, clicked to open, and drops down there is the black background and the gray highlight as always. The Button alone does change to the colors I supplied in the theme which is a good thing! Not to worry…I know you will get it straightened out in the next update.
I did try using all three recommendation together but there was no change in the effect. So I left the most recent change and removed the other 2.