$(document).ready(function() { 

// Tooltip
$("bottom_nav a").tooltip({ 
  
    // a little tweaking of the position 
    offset: [10, 2], 
 
    // use the built-in fadeIn/fadeOut effect 
    effect: "fade", 
 
    // custom opacity setting 
    opacity: 0.7, 
    
    event: mouseover,
 
     
});