your suggestion works fine, the gap between the submenue levels is now resolved and sublevel selection stabilized.
My final check however showed a final difference for the menue position:
The height of the main menue is shown as 51,8 pixel, the height of the sticky menue however only as 50,6 pixel.
The opening submenue seems to be absolutely positioned: it fits directly below the main menue. But it does not fit exactly below the sticky menue, because the sticky menue is a bit more narrow. Therefore there is a minor gap (1.2 pixel) between the sticky menue and the submenues. This gap can cause problems when selecting submenues.
Therefore my final question regarding these submenue positionings:
can I fix the sticky menue also to a height of 51,8 pixel, so that main menue and sticky menue have exactly the same height?
By this, the submenues should exactly fit below main menue and sticky menue!
Thanks and best regards,