I find this a very insightful application of the concept of colours to look at the problems of mixing code meant to run on slightly different and subtly incompatible runtimes, within the same code base, without calling out this distinction of "colour" by any particular mean of syntax, or tooling, or explicit documentation.

It's a good observation that helps, at least me, shed light and give a name to this problem that many will have experienced and struggled with.