RE: [css4-pseudo] The need for more powerful pseudo elements

> I like this idea. Flexbox’s 'order' property could be use to order the
> pseudo-elements of the same element, but we’d still need a way to
> consistently order pseudos that have the same 'order' value, or where
> it’s just not specified.

Indeed, that could work. 

For the same-order elements, it could be decided that the order is the priority order of the rules that define the pseudo-element (ie: selector specificity and then source order) but that require saving information about the selectors into the property values.

Also, it would cause unexpected reorders on :hover. 

   x::before(abc) { ... }
   x::before(cde) { ... }
   x:hover::before(abc) { ... }

Ordering things isn't an easy problem, as I found out ^_^