Change Header on Blog Posts (without changing the colour of the whole page)

Hi all (and @tuanphan)

I am trying to change the colour of my header in my blog posts... I am struggling to do so. I don't want to change the colour of the whole page, but in order for the rest of my site to work as is (like having the dynamic photo on the home page), I need it to be a dynamic and not set to theme. This is a nice-to-have and not a must-have, but I'd love some help figuring it out 🙂  Thank you!

Can you check site url + password again?