How to get rid of the ugly frame border in IE 9

I have a forum with a frameset (yes I know its old fashion but it works perfectly well).

And there is a chat frameset with 2 frames.

And in Internet Explorer 9 there have always been an ugly border between the two frames, despite have set values frameborder="0" and framespacing="0" and border="0".

I tried many times with all kinds of stuff, but then I found a way...

Here is what made my border disappear (the magic in bold text):

<frameset rows="*,127" border="0" framespacing="0" frameBorder="0"> 
  <frame src="chat.aspx#Down" scrolling="auto" name="chat" frameBorder="0" border="0" framespacing="0" style="border:none;height:101%;">
  <frame src="chat_input.aspx" scrolling="auto" name="chat_input" frameBorder="0" border="0" framespacing="0" style="border:none">
</frameset >

I think its the 101% height that places the border out of visibility, so it's more of a workaround... but it works! :-)