title: How to change visited links into unvisited links when something changed
body: <p>Is there any way to make a visited link back to unvisited without deleteing anything from hystory? I want to do that on a forum, when someone replies in a topic, it has to turn that topic link into unvisited.</p>
  
  <p>I am using this css:</p>
  
  <pre><code>a.newold:visited
  {color:#999999;}
  a.newold:link
  {font-weight: bold;}
  </code></pre>
  
  <p>and there is the list of topics:</p>
  
  <pre><code>&lt;a class="newold" href="read_topic.php?id=ID"&gt;TITLE&lt;/a&gt;
  </code></pre>
  
  <p>The thing is: When I click on a topic, it will be automatically updated as visited?</p>
  
  <p>I want something, (if is possible) that when I add a reply INSIDE that topic, its link will be updated as <strong>un</strong>visited</p>
  
  <p>More information about what I am seeking:</p>
  
  <p>Example: The topic name will be: TEST. 
  The topic first is unvisited, and it looks like:
  <strong>TEST</strong>;</p>
  
  <p>I click on it, I read it, it will look like:
  TEST;</p>
  
  <p>Then I add a reply in that topic;</p>
  
  <p>The topic will look <strong>un</strong>visited again: <strong>TEST</strong>;</p>
  
  <p>I think this is as clear as it can be.</p>
  
  <p>If I use some other variable like <code>$user</code> seen <code>topic_id</code>, it will be bad, because it is a large request, so I wonder if there is something that can be done without database requests.</p>