Hi,
It can be done with a slightly css modification. Please open sidebar-left.php and sidebar-page.php files from your theme directory, find this code :<div id="col2" class="<?php echo get_option('after_leftcol_color'); ?>">
and replace it with :<div id="col2" class="m_menu">
Next please add this code to your css :#colmask {background: #CF2700 !important;}
This should help
Jakub