Took me ages to do this, so FYI

The important bit is 'BorderColor="#D7E1E0" Frameborder=1'

<frameset cols="138,*" BorderColor="#D7E1E0" Frameborder=1 >

<frame name="sitemenu" src="sitemenu.html" scrolling="auto" marginwidth="4" marginheight="4" border="yes" framespacing="yes" >

<frame name="mainframe" src="mainframe.html" scrolling="auto" marginwidth="4" marginheight="4" border="yes" framespacing="yes" >

<noframes>

Happy Coding : - )

Thanks for that Hippy