Let it Go
The client wants this font changed or that color tweaked. Is it really that bad? You are there to solve their problems, after all. Unless you are your own client – do the work you were hired for. Good work. GREAT work.
Feedback and criticism are merely a difference of opinion. Don't take things personally. Egos are extremely fragile. They are bruised easily. Don't let yours become an impediment to doing good work.
Of course it's not an easy thing to do, but if you can learn to let go, you'll thank yourself later for having acquired the skill.