Combining two or more CSS selectors with a boolean condition

Question

Is there a way to combine two or more CSS selectors using a boolean condition - and, or, not?

Consider this

<

Answer 1

These should work:

&& = div.message.error {}
|| = div.message, div.error {}

Don't think you can do "not"

Edit: Just did a quick test to confirm:

    
        
    
    
        
None
        
Error
        
Message
        
Error Message
    

The "message", "error" and "error message" divs all have a green border and only the "error message" div has a red background.