Level

I'd say that's pretty good. Not 0.1 degrees. Not -0.1 degrees. Actually 0.0 degrees. Not even a lighter-than-ordinary-chocolate Malteser would roll of this beauty! My new shelf hanging career begins today.

Better not mention that this is attempt two. The first attempt yesterday - following the instructions for the 'floating' shelves with concealed fittings, the weight of the books (well below the advisable limit) had the shelf leaning forward at an odd angle, so I've had to add a bracket for support at the end.