Pseudo-selectors and @ declarations in style attributes?

I recently ran into a situation where I wanted to use a pseudo-selector for
an element and/or define an animation in an element's style attribute, and
nowhere could I find a solution. Is this possible with current syntax rules?
If not, are there any plans of implementation? As animations become more
common, I can imagine that in-attribute animations would become more
commonly wanted.

~6 out of 5 statisticians say that the number of statistics that either make
no sense or use ridiculous timescales at all has dropped over 164% in the
last 5.62474396842 years.