Imo as long as you're not targeting internet explorer, things are pretty consistent these days. All modern browsers are now "evergreen", which means they update

Imo as long as you're not targeting internet explorer, things are pretty consistent these days. All modern browsers are now "evergreen", which means they update automatically and silently, which is the best thing in the world for web devs. The only inconsistencies you get are some having implemented new features before others, not really outright contradictions, and even that isn't a very big gap these days.