pre.code {
      background: #dde;
      margin-left: 20px; 
      padding-left: 10px;
      width: auto;
      border: 1px solid #aaa;
    }
pre.abstract {
      background: #edd;
      margin-left: 20px; 
      padding-left: 10px;
      width: auto;
      border: 1px solid #aaa;
    }