You can and should break that up because I'm probably going to want to see screenshots to ensure that the branding changes make sense in context and everything looks consistent.

How would you do this? You'd either

1. Create N pull requests then merge all of them together into a big PR that would get merged into mainline at once 2. Do the same thing but do a bit of octopus merging since git merge can take multiple branches as arguments. Since most source control strategies are locked down, this isn't usually something that I can tell my juniors to do

The point of breaking things down like this is to minimize reviewer context. With bigger PRs there's a human tendency to try and hold the whole thing in your head at once, even if parts of the pull request are independent from others.