EasyBlog: CSS-override has no access to the linked images

Hello.

I just tried to create an css-override in EasyBlog using the vintage theme.
I did not make any changes in the override styles.css yet, I just copied it into the override-folder.

The override obviously works, but it has no correct access to the button-images in the menu-bar and the default admin-avatar.

Doing this I updated the links (automatically).

For example this link in the original styles.css:

../../default/images/blog-navi-prev.png

became this in the override-file in my template:
../../../../../components/com_easyblog/themes/default/images/blog-navi-prev.png

So for my opinion all images should be found. But unfortunately they are not shown. I attached a screenshot.

I suppose the mistake is on my side, but I don't find it.
I found nothing helpful in the forum or in the FAQ, so I would be grateful for help or advice.

Thanks!
Steffen.