Hi!

If you navigate to the "Issue Type" description page by clicking the icon next to "Issue Type" in the "Create Issue" dialog (aka: /ShowConstantsHelp.jspa?decorator=popup#IssueTypes) you will notice that the right edges of the text are cut off when wrapped. (If your screen is wide enough just make the browser window smaller to see the effect.)

What's at fault here is the CSS, more concretely that of the dd node:
dd {
float: left;
margin-top: 10px;
width: 100%;
}

The "width: 100%;" is what makes the box use more than the remaining space, dropping that from the CSS makes the overflow visible/readable and correctly wrapped.