postlight
Transitions
Unsure if this is supported, it might already be by adding css classes.
If so, we should document how to use them. I can see wanting to transition both the content (think counter) and the content area (think modal)
Transitions are, in theory, supported by the lifecycle-based classes that Trimmings adds while fetching and replacing content, but I honestly haven't done too much experimentation here to confirm that what's offered is sufficient for a broad set of desired effects.
I hope to either prove that it's sufficient, or add additional descriptive classes to affected DOM nodes, soon! Adding the good first issue label here because I'd love to see someone else pick this up and try to produce some examples of good transitions.
