Formatting text as bold when unread and normal when read

Hello,

I have an announcements component where I usually use html to add links, images etc. Currently this is filled with a list of links of posts I want to highlight, such as:

<a href="http://fr.community.norton.com/t5/Norton-Internet-Security-Norton/Nouvelle-Gamme-Norton-disponible/m-p/55380#U55380" target="_blank">Nouvelle Gamme Norton Disponible ! [en savoir plus]</a></b>

What I would like is that all links on the page display in bold until they have been clicked on by the user, so that when I add a new link to the list the user realises that there is new unread content in it.

Any clues as to how this can be done?

Thank you