added a comment - - edited
Thanks Urs, that fixed it when I attached it to the end of my styles_ie6.css. I realised that I had parentmetainclude set to false, but if I set it to true and use my original styles_ie6.css, it doesn't work. My theme is supposed to use custom_corners as its parent. Here's my config for comparison:
<?php // $Id: config.php,v 1.7 2007-08-09 11:47:24 urs_hunkler Exp $
$THEME->sheets = array('user_styles');
$THEME->standardsheets = array('styles_layout');
$THEME->parent = 'custom_corners';
$THEME->parentsheets = array('user_styles');
$THEME->modsheets = true;
$THEME->blocksheets = true;
$THEME->langsheets = false;
$THEME->block_l_min_width = 180;
$THEME->block_l_max_width = 210;
$THEME->block_r_min_width = 180;
$THEME->block_r_max_width = 210;
$THEME->courseformatsheets = true;
$THEME->metainclude = true;
$THEME->standardmetainclude = true;
$THEME->parentmetainclude = true;
$THEME->navmenuwidth = 50;
$THEME->makenavmenulist = false;
$THEME->customcorners = true;
$THEME->chameleonenabled = false;
$THEME->chameleonteachereditenabled = false;
$THEME->resource_mp3player_colors =
'bgColour=000000&btnColour=ffffff&btnBorderColour=cccccc&iconColour=000000&'.
'iconOverColour=00cc00&trackColour=cccccc&handleColour=ffffff&loaderColour=ffffff&'.
'font=Arial&fontColour=3333FF&buffer=10&waitForPlay=no&autoPlay=yes';
$THEME->filter_mediaplugin_colors =
'bgColour=000000&btnColour=ffffff&btnBorderColour=cccccc&iconColour=000000&'.
'iconOverColour=00cc00&trackColour=cccccc&handleColour=ffffff&loaderColour=ffffff&'.
'waitForPlay=yes';
$THEME->custompix = false;
?>
Also this in the quiz screen. Tabs overlapping each other.