anchor.diff:  
             First of all the specifity problem appears. In a local modifier case CSS code goes like this:
   
  -          ```
  +          ```css
             .block {
               display: block;
             }
  
positive.code: 
            Indeed you can have 2 main CSS classes at the same DOM node. In BEM we call it `mix`:
  
            ```
            <div class="block1 block2"></div>
            ```
  
  
negative.code: 
            In the case of global modifier, its properties can be redefined by the blocks if they follow modifiers in code:
  
            ```css
            .hidden { display: none }
            /* ... */
            .block { display: block }
            ```
            ```html
            <div class="block hidden">you still see me</div>
            ```
            One of the possible solutions to this problem is to rase the selector specifity of global modifiers by adding `!important` to them.
  