change header opacity

I don’t like the subtle but dirty looking mildly dark overlay that appears in the header of this theme. I just want the blue header i uploaded to display with white text and the bright white stars i created to just look white, like i made them.

if anyone can help explain to me how to get this gray extra tint off the header so it stops making my design look dingy, I would appreciate it so much. I tried to look for obvious things in the css but have not had any luck

thank you

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