I have difficulty in understanding the following CSS code

Question

I am trying to understand this code, I was not been able to find any article on the internet and I don't even know what kind of CSS code is this, a detailed explanation with some good example would be appreciated.

  .\36 u, .\36 u\24 {
     width: 50%;
     clear: none;
     margin-left: 0;
   }
   .\35 u, .\35 u\24 {
     width: 41.6666666667%;
     clear: none;
     margin-left: 0;
   }
   .\34 u, .\34 u\24 {
     width: 33.3333%;
     clear: none;
     margin-left: 0;
   }
   .proud{
     width:50%;
   }
   .\33 u, .\33 u\24 {
     width: 75%;
     clear: none;
     margin-left: 0;
   }
   .\32 u, .\32 u\24 {
     width: 16.6666666667%;
     clear: none;
     margin-left: 0;
   }
 .\31 u, .\31 u\24 {
    width: 8.3333333333%;
    clear: none;
    margin-left: 0;
   }