No, that works fine. It’s just that the default styles aren’t prepared for a colorful background so things look off.
But yes, my snippet is taken from my own forum and part of a larger customization. It’s a demo on what can be done, not what must be done. 
If you simply remove the html and .d-header blocks as well as the borders, bottom margin and padding on #main-outlet and set a white background, you basically get the same result without the weird body:before thing. 