Learning Objective: In this lesson you’ll learn how to build a multi-level navbar also known as a dropdown menu. An example of a dropdown menu in a vertical navbar is used in the left hand column of math-sceinces…
Here’s a full treatment of 2 level nav bars from Tom at jsfiddle;
You can read the original post at Stack Overflow http://stackoverflow.com/questions/9100344/pure-css-multi-level-drop-down-menu but it is a bit complicated.
the basic idea is that the navbar consists of a ul with links but navbar elements with a dropdown contain another ul nested within that element. Ie a ul within a ul.