Should be possible, but I don't get what's to like so much in unnecessary animations sucking your battery and making the whole experience awful on underpowered hardware.

I have Intel GPU with hidpi screen - Stripe's menu drops frames and spins up the fans.

Sadly `auto` values can't be animated. It can only be done with a bunch of hard-coded sizes and positions. Remove an item anywhere and you'll have to manually adjust.

> Sadly `auto` values can't be animated.

Sure, height:auto can't be animated - but max-height:800px, for example, can be used to similar effect.

No easing though. You can't avoid the "snapping" at the end

I agree. Browsers should communicate the user's OS settings of "animated GUI", so users can get what they prefer.