function mainmenu() {
    $(" #jnav ul ").css({ display: "none" }); // Opera Fix
    $(" #jnav li").hover(function() {
    $(this).find('ul:first').css({ visibility: "visible", display: "none" }).slideDown(200);
    }, function() {
        $(this).find('ul:first').css({ visibility: "hidden" });
    });
}

$(document).ready(function() {
    mainmenu();
});

/*
.fadeIn(400) or .slideDown(400)
*/