@media only screen and (max-width: 768px) {
    .custom-pre
    {
         white-space: pre-wrap;       /* Since CSS 2.1 */
white-space: -moz-pre-wrap;  /* 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+ */
    }
}