Grid separator lines on the header

What css object do I need to address to change the vertical separator lines on the header? (Reference page http://test.tbnonline.com)

Specifically I want to remove the one to the right of subject so that the bar cleanly goes all the way to the right.

This is my current css:

#BroadcastLog .aw-alternate-even {background: #cadcf2 }
#BroadcastLog .aw-alternate-odd {background: #ecf3fb;}
#BroadcastLog .aw-rows-current {background: #C9D9EE;}
#BroadcastLog .aw-column-1 {border-right:1px solid #999; }
#BroadcastLog .aw-column-8 {border-right:1px solid #999; }
#BroadcastLog a {color:#000000; }
#BroadcastLog .aw-grid-row {color: #000000; font-size:0.9em; margin-bottom:0px; margin-top:0px; height:13px;}
#BroadcastLog .aw-mouseover-row {background: #B9C9DD;}
#BroadcastLog .aw-grid-headers {color:#FFF; font-size:1.1em; border: 1px solid #F00;}
#BroadcastLog .aw-grid-header .aw-item-box {background-image:url(Andy/MenuButton.jpg); }

#BroadcastLog-separator-5 {display:none}

BRAVO! Thanks.

THat also disabled column resizing, is there a way to change the separator from a white verticle bar to someting not white. I tried color, background-color. what is actually producing the verticle white line?

Thanks.

It's background image, so the style should be -

#BroadcastLog-separator-5 {background:none!important}