Layers are supported in all modern browsers!
To get a more extensive overview of support in your current browser,
see the
Web Platform Tests.
Scroll down the list to find all the layer-* tests.
Layers allow you to manage the cascade more explicitly,
specifying exactly what stlyes override other styles,
without worrying about specificity or source order.
For example, we can ensure that a error state
always takes priority over other styles: