Description
Describe the problem
The way CSS transitions are currently handled they inject inline attribute styles into the element. This requires the site use style-src 'unsafe-inline'.
Describe the proposed solution
I'm not entirely sure how this works, but I've seen some inline attribute styles be accepted under style-src 'self' while others are not. Specifically, these spinners seem to work just fine even under a strict CSP.
It appears as though defining CSS variables inline is actually allowed? I haven't seen any documentation about that in particular, though. If true, Svelte transitions could in principle be changed to work like the above, where the transitions are defined in CSS documents, configured by inline variables, and applied by a class change.
This is essentially a cnange only in the internal handling of transitions (and possible animations?), and wouldn't have any effect on how they are used in Svelte code.
Alternatives considered
Don't use transitions if you want a strict CSP.
Make your own transitions by hand.
Importance
would make my life easier