I was just on a web page with this section on the left with navigation links, nothing big or out of the usual, but when i moused over the links, they changed in appearance, they changed in size, and underlined, after opening the source i found out that it was java script, how (detail please) do you do it? and where can i learn more about it, tutorials and such? below is the code i picked out:

<style type="text/css">

<!--

A:visited {text-decoration: none;}

A:hover {text-decoration: underline;}

A:link {text-decoration: none;}

A:active {text-decoration: none;}

-->