Header image behind site logo

Hello there, first of all thank you for your theme, I really like it! I would like to add a header image to my website www.spielfrei.at If I activate it via the customizer -> header-image it looks like this: https://imagebin.ca/v/3erM76p2fZ4u I want to position the header image behind the site logo. Can you please help me? Many thanks and greetings from Austria, Alex