Version: 4.3.2 (KDE 4.3.2) (using 4.3.4 (KDE 4.3.4), Debian packages) Compiler: cc OS: Linux (i686) release 2.6.30-8-686-latitude e.g. http://tools.ietf.org/html/rfc1323 should be rendered with a fixed-width font, because all the text lies within a pre tag, but webkit kpart chooses a proportional font.
Update to KDE 4.4. The issue was upstream in QtWebKit and has been addressed in Qt 4.6. See https://bugs.webkit.org/show_bug.cgi?id=22896