I know a AdSense Plugin already exist (nodebb-plugin-google-adsense). But it is not compatible with 0.7.x and the developer does not update it. So if someone could make a new one or update the existing one - that would be nice.
I can add the image. Where do you want the opacity, on the image?
image + opacity
Sent a PR
I re-positioned the bg so that opacity doesn't affect the text. And there's an admin page where you can adjust the opacity.
@yariplus thank you man!
edit: text shadow?
@lombisi Added text shadow to the PR.