I had this issue of long lines especially when u cut and paste codes from different ide's into my desktop application. 

simplest thing to do would be to add a width="99%"  in pre tag

or use this css add it to the html page

pre {
 white-space: pre-wrap;       /* css-3 */
 white-space: -moz-pre-wrap !important;  /* Mozilla, since 1999 */
 white-space: -pre-wrap;      /* Opera 4-6 */
 white-space: -o-pre-wrap;    /* Opera 7 */
 word-wrap: break-word;       /* Internet Explorer 5.5+ */
}