For some reason FireFox does not wrap code or other text (with no good word-breaking point) that is in a PRE tag. I noticed the problem when I was trying to stop a Blogger template from truncating (cutting of) the end of lines (that were too long). I want FireFox to wrap the long lines just like Internet Explorer. As it turns out, it is quite easy to fix. Just add the following to your CSS styles.
white-space: pre-wrap; /* css-3 */
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+ */