Visual Verification

Core rule

If appearance is part of the requirement, the rendered result is the evidence.

Source code, DOM structure, CSS, a scene tree, a passing test suite and a clean build are not proof that something looks right. They are proof that it was described right. Those are different, and the gap between them is where almost every "finished" UI that the user immediately calls broken lives.

The loop

implement -> launch/render -> capture the actual output -> LOOK at it
   -> find defects -> fix -> render again -> look again -> only then done