Sorry, to be one of those guys but Android O as you may probably know has the "inverted" theme, which I found kind of strains my eyes, not too much that it's a problem but it still does a little, I know that there's suppose to be a Device Theme "menu" under the display settings but it's just not there on my phone for some reason. So I'm not sure what to do now.
P.S. I have a Google Pixel XL
