You don't need Java or JavaScript for that. CssPlay has lots of pure CSS menus.
http://www.cssplay.co.uk/menus/
The type which has a horizontal dropdown level is called a dropline menus, like
http://www.cssplay.co.uk/menus/cssplay-pushpull.html
and
http://www.cssplay.co.uk/menus/doors_drop_line_two.html
Copy/paste the relevant style section from the CSSplay head section style tag and copy/paste from the body markup, then edit it.
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.