Version:           4.0 (using KDE 3.1.5)
Installed from:     (testing/unstable)
Compiler:          gcc version 3.3.3 20031229 (prerelease) (Debian)
OS:          Linux (i686) release 2.4.22

in the follwing contruct ...

<style>
address {width:40ex; height:20ex; border:1px solid red; background-color:#FBFBFB; z-index:99; display:run-in; position:relative; top:-44em; left:58em}
</style>

<iframe style="z-index:1" src="blah.html" width="100%" height="500" frameborder="1"></iframe>

<p class="address">BlahBlah</p>

the page consist of a form and the follwing iframe.
the css-formated "window" inside the <p>-tags will not be layed over the iframe, instead the iframe covers it completely.
if moving the css-box so it should appear layed over the form, it does not cover text-fileds/-areas, only the form-background.
in mozilla it works, so i'm pretty sure it's not my fault :-)