Accessing HN with Firefox (if your web history is turned on) does exactly that[1]. No extension is necessary. The same is true for every other browser since the CSS file it clearly says:<p><pre><code>    a:link    { color:#000000; text-decoration:none; }
    a:visited { color:#828282; text-decoration:none; }
</code></pre>
[1] <a href="http:&#x2F;&#x2F;i.imgur.com&#x2F;CqKW1yK.png" rel="nofollow">http:&#x2F;&#x2F;i.imgur.com&#x2F;CqKW1yK.png</a>