Styling WP Custom Menu elements

I have positioned the WP custom menu widget in my left sidebar (http://monumentpress.com), and I simply want to style the page links in this menu so that the link for the current page is distinguished by a different color, while the rest of the (inactive) links keep the default link color. I have read the other posts on this forum, regarding custom menu styling, but I cannot figure out how to make this work.

When I try to style this using ATO>HTML/CSS Inserts, it appears my styles are being somehow overwritten by the 'div.widget a:link' attribute. Can someone please guide me with the proper syntax for selecting my links within the custom menu widget, in this instance?