Is there any way to mark articles as read so that they don't occupy the screen any more?

No, but each article you read automatically is archived in "Viewed" section for an easy access.

Btw, thanks by your feedback. We will add a switch in the 1.1 version (coming in a few days) to auto-delete the viewed posts from your main feed and archive them in your viewed tab only :)

That'd be great! Looking forward to it.