A { text-decoration:none; }
A:hover { text-decoration:underline; }Enjoy!
[Editor's note: Since there are literally hundreds of CSS commands you can use to create your own customized browsing experience, I could literally run customized CSS file hints forever ... but I won't, as that's not what the site is about! So consider this hint as a jumping-off point for further CSS file exploration; what you learn from here on is up to you. I won't run many other hints regarding customizing CSS files, as the scope is just too broad, and there are many other hint topics to cover...]

