Lighting with slabs and stairs don't look right compared to blocks.

I honestly though it was be as smooth as full blocks were/are.
I think it should have been just as smooth.

The lighting didn't fit right with what it should have been.
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Steps to Reproduce:
1. Grab a slab or stair block of any kind out of the creative/survival inventory.
2. Place one of the two or both as a roof or wall.
3. Observe.

In the picture below, the dark photo at the bottom is how it should look, as you can see, the room is completely dark with no bright rims on the edges. Please fix this, this "bug" as I like to call it. It has been in the game since it first came out. And i'm sure we would all love it if it was fixed.