As a general rule, foreground should be more detailed and background should be less. Things that are further away have less definition in our eyesight and things closer up have more. If they're RIGHT UP ON US they might blur out of focus a little, but I'm not sure if you want to go that far.
The bright yellow of the background isn't really working though I think, I'd fade that out some into more of a parchment color so it has a more storybook feel to it.