var nav_1_in = new Image();
var nav_2_in = new Image();
var nav_3_in = new Image();
var nav_4_in = new Image();
var nav_5_in = new Image();
var nav_6_in = new Image();

nav_1_in.src = "images/nav_1_in.png";
nav_2_in.src = "images/nav_2_in.png";
nav_3_in.src = "images/nav_3_in.png";
nav_4_in.src = "images/nav_4_in.png";
nav_5_in.src = "images/nav_5_in.png";
nav_6_in.src = "images/nav_6_in.png";