:visited

The :visited CSS pseudo-class lets you select only links that have been visited. This style may be overridden by any other link-related pseudo-classes, that is :link, :hover, and :active, appearing in subsequent rules. In order to style appropriately links, you need to put the :visited rule after the :link rule but before the other ones, defined in the LVHA-order: :link — :visited — :hover — :active.

<!DOCTYPE html>
<html>
    <head>
        <style>
            a:visited {
                color: #F00;
            }
            /* another style 
            a:visited {
                background-color: white;
            } */
            
            /* table rows with class col will collapse */
        </style>
    </head>
    <body>
    	<a href="http://www.loopandbreak.com">Ayunor Learning</a>
    </body>
</html>