Simple sibling collapsing tests:
   
    This has a top/bottom 10px margin
    This has a top/bottom 10px margin
    This has a top/bottom 10px margin
    
   Simple generational + sibling collapsing tests:
   
    
     This has a top/bottom 10px margin
     
    
     
      This has a top/bottom 10px margin
      
     
    
     
      
       This has a top/bottom 10px margin
       
      
     
    
   Verify that borders/padding interfere with
    sibling + generational collapsing:
   
    This has a top/bottom 10px margin
    This has a top/bottom 10px margin
    This has a top/bottom 10px margin
    
   
    This has a top/bottom 10px margin
    This has a top/bottom 10px margin
    This has a top/bottom 10px margin
    
   
    This has a top/bottom 10px margin
    This has a top/bottom 10px margin
    This has a top/bottom 10px margin