With several heavily loaded questions here on meta and the StackExchange meta, -
MathOverflow updated site theme is ready for testing!
Responsive Design Themes - What can sites customize and how can they get changes implemented?
Ch-ch-ch-changes: Left nav, responsive design, & themes
Rollout of new network site themes
and several others - I became totally confused. Despite seemingly more-than-exhaustive information provided, I could not find any definite answer to the question
Which of the design changes are unavoidable and why?
If there is somewhere a list of such changes, could somebody please give me a link?
Let me add one more thing. There is a frightening tendency of turning metas upside down. Literally all of the linked questions and many others to be found on both metas are not questions at all. They are actually answers to questions nobody asked. And they are followed, instead of answers, by several angry questions.
It is understandable but somehow unpleasantly symptomatic.