Konq has some problems
Konqueror has some rendering problems. I use Mozilla, but I test my site in Konqueror and I frequently have to tweak or re-work my style sheets so that Konqueror can display them without triggering a bug.
My site is strict xhtml 1.1 and valid style sheets, all checked with the w3c validators, so I'm not doing anything wrong.
My most recent problems were with the width of list items. I'd set them to 33%, but if the list items contained links, some list items would shrink to minimum width when I hovered the mouse over them. It's just a bug, it'll get fixed. (It might already be fixed. Try the latest version of Konqueror if you are using and old version) Either that or use Mozilla for any sites that trigger Konq bugs.