Hi! Couldn't find any info about platform dependent code in BEM.
My trouble looks like this: as QA responsible for a huge web-service I would like to minimize risks and test both: mac and windows. But its rather expencive to run all tests. Whith of them look more risky?
At Yandex we run selective tests for each pull request which means that only affected platforms are tests. But as for releases we test everything so it's a kind of balance.