The idea here is to provide rapid access deep into a site to mouse users, without burdening keyboard users with lots of extra links to tab through. For example, mouse users have rapid access to the "panther" page from the "cats" menu, whereas a keyboard user would go to the "cats" page and select "panthers" from some further navigation available there.
JavaScript is used to add/remove the submenus in order not to depend on the styling layer and in order to avoid the flickering associated with :hover.
This code example has been designed to be library-independent; similar implementations should be possible in the library of your choice.
Note: "birds" and "meat" do not have submenus in this example.
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