Does anyone have a filter for alert / callout styling?

[FeralFlora]

Since alerts are very minimally styled by default, they need to have styling applied using something like a filter. Without that, they're not really appealing to use.

Unfortunately, I haven't seen any such filter floating about, and I don't have the experience to create one myself.

So I was wondering if anyone here had come across or created such a filter for alert / callout styling?

[FeralFlora]

Sorry, meant to create this in the Pandoc repo...