Sliding CSS underline on hover - color transition not working on visited link

I created a navigation that underlines links on hover (sliding underline starting in the middle, extending outward), and also converts the link from dark green to light green. This works great unless one of the links has been clicked and it becomes a "visited" link: when I click the visited link again, the sliding underline still works, but the color won't transform from dark to light green, it just stays dark - green. I've tried everything I can think of but can't get the visited link to convert it to color as an unvisited link.

HTML:

<div id="topNavigation">
    <ul>
        <li><a href="encyclopedia.html">ENCYCLOPEDIA</a></li>
        <li><a href="journal.html">JOURNAL</a></li>
        <li><a href="society.html">SOCIETY</a></li>
        <li><a href="about.html">ABOUT</a></li>
    </ul>
</div>

      

        
        
        
      

    

CSS

#topNavigation a:link {
    font-family:"Quicksand-Regular", "Trebuchet MS", Verdana, Arial, Helvetica, sans-serif;
    font-size:20px;
    position:relative;
    color:#00590d;
    text-decoration:none;
    transition:color .35s;
    -webkit-transition:color .35s;
}

#topNavigation a:hover {
    color:#7ead34;
}

#topNavigation a:before {
  content: "";
  position: absolute;
  width: 100%;
  height: 2px;
  bottom: 0;
  left: 0;
  background-color: #7ead34;
  visibility: hidden;
  -webkit-transform: scaleX(0);
  transform: scaleX(0);
  -webkit-transition: all 0.3s ease-in-out 0s;
  transition: all 0.3s ease-in-out 0s;
}

#topNavigation a:hover:before {
  visibility: visible;
  -webkit-transform: scaleX(1);
  transform: scaleX(1);
}

#topNavigation a:visited {
    color:#00590d;
    text-decoration:none;
}

      

        
        
        
      

    

You can see what I'm talking about here: http://www.religionandnature.com/website2015/

The link to the "Encyclopedia" page is visited and the color does not cross. Other links are not visited and work fine. Any suggestions are appreciated.