Decouple Your CSS From HTML With Reusable Modules
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thenittygritty.co
But I would never use semantic class names, that just seems like a huge waste of time. If I'm building a page, I shouldn't have to touch a SASS file unless I'm actually creating new styles.
Technically speaking, a class name should never be something like "download-whitepaper" - IDs are used to uniquely identify things, not classes.