body {
   font: 24px Helvetica;
   background: #999999;
  }

  #main {
   min-height: 100px;
   margin: 0px;
   padding: 0px;
   display: -webkit-flex;
   display:         flex;
   -webkit-flex-flow: row;
           flex-flow: row;
   }
 
  article {
   display: block;
   margin: 4px;
   padding: 5px;
   min-height: 100px;
   border: 1px solid #eebb55;
   border-radius: 7pt;
   background: #F06;
        
      
   }
  
    
   #main > section {
   margin: 4px;
   padding: 5px;
   border: 1px solid #cccc33;
   border-radius: 7pt;
   background: #ddd088;
   -webkit-flex: 3 1 60%;
           flex: 3 1 60%;
   -webkit-order: 2;
           order: 2;
   }
      
      
  #main > nav {
   margin: 4px;
   padding: 5px;
   border: 1px solid #8888bb;
   border-radius: 7pt;
   background: #ccccff;
   -webkit-flex: 1 6 20%;
           flex: 1 6 20%;
   -webkit-order: 1;
           order: 1;
   }
  
  #main > aside {
   margin: 4px;
   padding: 5px;
   border: 1px solid #8888bb;
   border-radius: 7pt;
   background: #ccccff;
   -webkit-flex: 1 6 20%;
           flex: 1 6 20%;
   -webkit-order: 3;
           order: 3;
   }
 
  header, footer {
   display: block;
   margin: 4px;
   padding: 5px;
   min-height: 100px;
   border: 1px solid #eebb55;
   border-radius: 7pt;
   background: #CFC;
   }
 
  /* Demasiado estrecha para soportar tres columnas */
  @media all and (max-width: 640px) {
  
   #main, #page {
    -webkit-flex-flow: column;
            flex-flow: column;
   }

   #main > article, #main > nav, #main > aside {
    /* Devolverlos a documentar orden */
    -webkit-order: 0;
            order: 0;
   }
  
   #main > nav, #main > aside, header, footer {
    min-height: 50px;
    max-height: 50px;
   }
  }