Some developers think that code reviews should only be about the style of the code and nothing else, I strongly disagree.
If we look only at code style and ignore the desired outcome of the unit of work, we could potentially be reviewing code that will be replaced. What I mean by this is – if we review the code on Monday and say “all good” then the developer ends up realising at a later stage that – regardless of how beautiful the code was, the implementation is not working as intended, the code will probably end up being refactored and our review efforts now wasted.
As reviewers what we should be doing is running the implementation as we review, whether than be on a development environment or pulling a branch. We can use our eyes/ high fidelity designs/ browser plugins (CSS Ruler for example) to do some basic QA on the implementation and make sure it is going through in reasonable shape.
We should use our QAs to tell us what is not obvious, not the obvious. Being thorough at this earlier stage will speed things up in the long run.