Old browsers will just ignore it, just like if you give them nested SCSS without pre-processing it first. And for those that need to support older browsers, it'

Old browsers will just ignore it, just like if you give them nested SCSS without pre-processing it first. And for those that need to support older browsers, it'd probably still run through some sort of processor to output CSS for the older browsers. I see no reason to need to tell the parser what rules to parse for given how CSS works. As far as having numerous `@nest` definitions, I don't know if your concern is file size, but if so, that really isn't an issue - assuming use of gzip (or some similar compression), there is almost zero difference in file size for repeated use of `@nest`. I did a bunch of testing related to multiple @media blocks versus a single one (a long time ago) and found it didn't make any significant difference in file size - and that adds significantly more characters in the uncompressed version than @nest does.