The screenshot in my first message was with a placeholder to demonstrate you the behavior on mobile. Right now I do not use a brand logo, only the text “Bürostuhl Experte”.
When I upload a header/ logo with the recommended size 300 x 76 px it is in 2 lines on many mobile devices because of the logo width.
Therefore I uploaded a smaller logo with 270 x 69 px so that it is in 1 line: https://www.saege-experte.de/ (see mobile viewport). The menu icon is sticky on top of the blue bar and therefore not in line with the logo (I tested different logo sizes).
Is there also a CSS code to have the menu icon always in the middle of the header (= a bit lower) so that it is in line with the logo?