Well, all I changed was a line in the stylesettings.php (what Azala said to) and Firefox now displays the frame fine, fits 100% inside the table cell.
But now IE doesnt display the scroll bar, OR let me scroll down any way at all myself.
And in both of the browsers, the top cell logo now aligns to the top, instead of the middle as I have tried to specify (and how it used to before adding the "div { height:100%; }" line)
This is the stylesettings.php include file:
<style type="text/css">
<!--
body {background-color: #E7E3EF;}
.style2 {font-size: 10px; font-family: Verdana;}
.style3 {font-family: Verdana; font-size: 12px;}
a:link {text-decoration: none;}
a:visited {text-decoration: none;}
a:hover {text-decoration: underline;}
a:active {text-decoration: none;}
div { height:100%; }
-->
</style>
So now I either have the iframe dodgy in FireFox, or I have the dodgy-looking logo in all...unless anyone has any info?