Customized sidebar sometimes out of alignment

Hi there,

the block element is a fantastic way to create customized sidebars for visitors showing certain interests.

I have created an element type "right sidebar".

Location is

posts: category1
posts-category-archive: category1

What´s confusing: Sidebar is perfectly showing up on archive page but on single posts it is out of alignment.

Cache was deleted, WP Fastest cache disabled, nothing seems to improve this. Could anybody give me a hint?

Thanks much
Volker