<style type="text/css">
pre {
background: #EEEEEE;
border: 1px solid #CCCCCC;
width: 100%;
/* overflow: scroll; */
/* IE only */
word-wrap: break-word;
/* non-standard */
white-space: normal;
}
</style>
<pre>
this is a very very very very very very very very very very very very
+very very very very very very very very very very very very very very
+ very very very very very very very very very very very very very ver
+y very very very very very very very very very very very very very ve
+ry very very very very very very very very very very very very very v
+ery very very very very very very very very very very very very very
+very very very very very very very very very very very very very very
+ very very very very very very very very very very very very very ver
+y very very very very very very very very long string
</pre>
update: added IE only CSS
update 2: added non-standard CSS and commented out overflow: scroll as its no longer needed
Hrm. It seems that white-space is standard. IE doesn't support it however ... but who uses that these days anyway :) Above code works in all browsers I have at hand in any case
update 3: started from scratch
After more deliberation, it seems I've still not solved your problem - except inadvertantly in IE - so heres another attempt. Its not perfect, but its closer.
<style type="text/css">
pre {
padding: 0.5em;
background: #EEEEEE;
border: 1px solid #CCCCCC;
overflow: auto;
/* non-standard */
/* white-space : normal; */
}
* html pre {
/* IE only */
word-wrap:break-word;
}
</style>
<pre>
this is a very very very very very very very very very very very very
+very very very very very very very very very very very very very very
+ very very very very very very very very very very very very very ver
+y very very very very very very very very very very very very very ve
+ry very very very very very very very very very very very very very v
+ery very very very very very very very very very very very very very
+very very very very very very very very very very very very very very
+ very very very very very very very very very very very very very ver
+y very very very very very very very very long string
and
spacing of things
</pre>