An exhaustive way of supporting it in almost all browsers:
pre {
white-space: -moz-pre-wrap; /* Mozilla, supported since 1999 */
white-space: -pre-wrap; /* Opera */
white-space: -o-pre-wrap; /* Opera */
white-space: pre-wrap; /* CSS3 - Text module (Candidate Recommendation) http://www.w3.org/TR/css3-text/#white-space */
word-wrap: break-word; /* IE 5.5+ */
}
I had the same problem not long ago and had found the solution here:
http://codingforums.com/showthread.php?t=43293