Why we don't have a parent selector

On a seemingly regular basis, I see this discussion come up as to whether CSS should have a particular feature like the parent selector and while I haven't worked on a browser engine, I have my theories. In short: performance. How CSS gets evaluated With work, I've had to do quite a bit of examination of performance. We run a number of tools over an application to determine where the bottlenecks a

[efcl]

CSSは右から左へ評価する。親を指定するセレクタがない理由。 孫やユニバーサルセレクタの効率の悪さの話 http://twitter.com/azu_re/status/26997392273

[diveintounlimit]

なるほどやっぱり。

[ama-ch]

おもしろかった

[ethertank]

何故、親を指定するセレクタがないか。重いからだよ。みたいな。