CSS questions

Wouter 60,

another interesting way to do it  . I was wondering if it's possible to define row_red  as row_without_color plus the color, something like row_red  would inherit from row_without_color. I googled but didn't find something I can understand. I have questions about CSS like:

• why the dot '.' before the name
  
• why one sometime sees name_1 name_2 { ... }
  

Thanks