CSS

 pre {
   font-size: 12px;
   padding: 0;
   margin: 0;
   background: #f0f0f0;
   border-left: 1px solid #ccc;
   border-bottom: 1px solid #ccc;
   line-height: 20px;
   background: url(//img.webme.com/pic/-/-index-/pre_code_bg.gif) repeat-y left top;
   width: 600px;
   overflow: auto;
}