Page hero vertical alignment

So it is probably very obvious, but I need help as I am new to this theme!
I have a page hero setup as per guide with merge with content.
I set the vertical alignment to center, it works fine on desktop - but smaller screens it aligns at bottom of screen. If I set vertical alignment to top then it aligns to top on desktop and center on smaller screens.
I want it all in the center! What easy thing am I missing?