image1 = new Image();
image1.src = "images/nav1_on.gif";

image2 = new Image();
image2.src = "images/nav2_on.gif";

image3 = new Image();
image3.src = "images/nav3_on.gif";

image4 = new Image();
image4.src = "images/nav4_on.gif";

image5 = new Image();
image5.src = "images/nav5_on.gif";

image6 = new Image();
image6.src = "images/nav6_on.gif";

image7 = new Image();
image7.src = "images/nav7_on.gif";

image8 = new Image();
image8.src = "images/nav8_on.gif";

image9 = new Image();
image9.src = "images/nav9_on.gif";

image10 = new Image();
image10.src = "images/nav10_on.gif";

function popup(text){
    document.getElementById('popup_box').style.display = 'block';
    document.getElementById('popup_content').innerHTML = text;
}

function popup2(text){
    document.getElementById('popup_box2').style.display = 'block';
    document.getElementById('popup_content2').innerHTML = text;
}

function popup3(text){
    document.getElementById('popup_box3').style.display = 'block';
    document.getElementById('popup_content3').innerHTML = text;
}

function popup4(text){
    document.getElementById('popup_box4').style.display = 'block';
    document.getElementById('popup_content4').innerHTML = text;
}