SASS parses along those exact nesting rules, so clearly it's possible for the browser to do it as well. Just a question of performance hit at runtime. In the e

SASS parses along those exact nesting rules, so clearly it's possible for the browser to do it as well. Just a question of performance hit at runtime. In the end having the runtime be fast is likely more important than perfect syntax (as we can still pre-compile via better syntax), but the actual numbers and real world use cases matter a lot. Are these worst case performance scenarios actually realistic or common? I didn't see anybody speaking to that, but also haven't followed this issue in years. I have seen on a lot of the web standards discussions that many of the contributors will pose theoretical worst case situations as something that should meaningfully impact design of a feature, when those worst case scenarios are extremely rare and unrealistic in practice.