Warning messages - Use of color vs Consistency

[giacomo-petri]

There are cases where warnings are presented with either a light orange background (e.g. https://www.w3.org/WAI/ARIA/apg/patterns/slider/examples/slider-seek/) or a light red background (e.g. https://www.w3.org/WAI/ARIA/apg/patterns/slider-multithumb/).

If the intention is to give greater prominence to the ones with a red background, akin to alerts, we should consider changing the label from "Warning" to "Alert."
Conversely, if the purpose remains consistent, it would be advisable to maintain uniformity by using the same background color for all warnings.

For reference, here's a screenshot illustrating the difference between orange and red warnings:

I am happy to submit a pull request to implement these changes once a decision has been reached.