(Preference Lite) Adding vertical divider between main content and sidebar

Hi,
My side bar is not very long so as you scroll down the page, the page loses interest because of lack of color. I’d like to add a vertical line to divide the main content from side bar (all the way down past the end of side bar).

I have already tried this.
http://wordpress.org/support/topic/adding-dividing-line-to-separate-sidebar-from-main-content
And this:
http://en.forums.wordpress.com/topic/adding-colored-vertical-line-to-separate-content-from-sidebar?replies=11

But nothing seems to change. Please let me know how I can get it to work.

I appreciate the help. Thanks.