Edit in JSFiddle

  /* Main Containers */

  body {
      margin: 0;
      }
                                      
  #wrapper {                          
    width: 960px;                     
    }                                 
                                      
  #grid {                             
      float: left;                      
      width: 960px;                     
      margin: 0;                        
      padding: 0;                       
      background: white;                
      }                                 
                                      
  .block {                            
    position: absolute;               
    border: 1px solid black;          
    }                                 
                                      
  .inner {                            
    height: 100%;                     
    width: 100%;                      
    }                                 
                                      
  .s1x1 {                             
    height: 240px;                    
    width: 240px;                     
    }                                 
                                      
  .s2x1 {                             
    height: 240px;                    
    width: 480px;                     
    }                                 
                                      
  .s3x1 {                             
    height: 240px;                    
    width: 720px;                     
    }                                 
                                      
  .s4x1 {                             
    height: 240px;                    
    width: 960px;                     
    }                                 
                                      
  .s1x2 {                             
    height: 480px;                    
    width: 240px;                     
    }                                 
                                      
  .s2x2 {                             
    height: 480px;                    
    width: 480px;                     
    }                                 
                                      
  .s3x2 {                             
    height: 480px;                    
    width: 720px;                     
    }                                 
                                      
  .s4x2 {                             
    height: 480px;                    
    width: 960px;                     
    }                                 
                                      
  .s1x3 {                             
    height: 720px;                    
    width: 240px;                     
    }                                 
                                      
  .s2x3 {                             
    height: 720px;                    
    width: 480px;                     
    }                                 
                                      
  .s3x3 {                             
    height: 720px;                    
    width: 720px;                     
    }                                 
                                      
  .s4x3 {                             
    height: 720px;                    
    width: 960px;                     
    }                                 
                                      
                                      
  /* Blocks Position */               
                                      
  .p0x0 {                             
    top: 0px;                         
    left: 0px;                        
    }                                 
                                      
  .p1x1 {                             
    top: 0px;                         
    left: 240px;                      
    }                                 
                                      
  .p2x0 {                             
    top: 0px;                         
    left: 480px;                      
    }                                 
                                      
  .p3x0 {                             
    top: 0px;                         
    left: 720px;                      
    }                                 
                                      
  .p0x1 {                             
    top: 240px;                       
    left: 0px;                        
    }                                 
                                      
  .p1x0 {                             
    top: 0;                           
    left: 240px;                      
    }                                 
                                      
  .p1x1 {                             
    top: 240px;                       
    left: 240px;                      
    }                                 
                                      
  .p2x1 {                             
    top: 240px;                       
    left: 480px;                      
    }                                 
                                      
  .p3x1 {                             
    top: 240px;                       
    left: 720px;                      
    }                                 
                                      
                                      
  .p0x2 {                             
    top: 480px;                       
    left: 0px;                        
    }                                 
                                      
  .p1x2 {                             
    top: 480px;                       
    left: 240px;                      
     }                                
                                      
  .p2x2 {                             
    top: 480px;                       
    left: 480px;                      
     }                                
                                      
  .p3x2 {                             
    top: 480px;                       
    left: 720px;                      
    }                                 
                                      
                                      
  .creditline {                       
    position: absolute;               
    top: 750px;                       
    left: 10px;                       
    font-family: Helvetica, sans-serif;
    font-size: 13px;                  
    color: gray;                      
  } 

<div id="wrapper">
  <div id="grid">

          <div class="block s2x1 p0x0"></div><div class="block s1x2 p3x0"></div><div class="block s1x1 p2x0"></div><div class="block s2x2 p1x1"></div><div class="block s1x1 p3x2"></div><div class="block s1x2 p0x1"></div>
  </div>
</div>

<span class="creditline">Grid Builder by Dubberly Design Office</span>