// Used to change text size (measured in %)
var pageFontSize = 110;
var head1FontSize = 180;
var head2FontSize = 130;
var fontFamily = "Helvetica, Arial, sans-serif";

function changeFontSize(v) {
    var increment = 5;

    var maxFontSize = 130;
    var minFontSize = 80;
    
    var maxHead1FontSize = 200;
    var minHead1FontSize = 150;

    var maxHead2FontSize = 150;
    var minHead2FontSize = 100;

    var i, j, k, l, m = 0;

    pageFontSize += v * increment;
    if (pageFontSize > maxFontSize) {
        pageFontSize = maxFontSize;
    } else if (pageFontSize < minFontSize) {
        pageFontSize = minFontSize;
    }

    head1FontSize += v * increment;
    if (head1FontSize > maxHead1FontSize) {
        head1FontSize = maxHead1FontSize;
    } else if (head1FontSize < minHead1FontSize) {
        head1FontSize = minHead1FontSize;
    }

    head2FontSize += v * increment;
    if (head2FontSize > maxHead2FontSize) {
        head2FontSize = maxHead2FontSize;
    } else if (head2FontSize < minHead2FontSize) {
        head2FontSize = minHead2FontSize;
    }

    var pageElements = document.getElementsByTagName("p");
    var anchorElements = document.getElementsByTagName("a");
    var head1Elements = document.getElementsByTagName("h1");
    var head2Elements = document.getElementsByTagName("h2");
    var navElements = document.getElementById("navcontainer");    
    
    for(i=0; i< pageElements.length; i++){
        pageElements.item(i).style["font"] = pageFontSize + "% " + fontFamily;
    }
    for(j=0; j< anchorElements.length; j++){
        anchorElements.item(j).style["font"] = pageFontSize + "% " + fontFamily;
    }
    for(k=0; k< head1Elements.length; k++){
        head1Elements.item(k).style["font"] = head1FontSize + "% " + fontFamily;        
    }
    for(l=0; l< head2Elements.length; l++){
        head2Elements.item(l).style["font"] = head2FontSize + "% " + fontFamily;        
    }
    for(m=0; m< navElements.length; m++){
        navElements.item(m).style["font"] = pageFontSize + "% " + fontFamily;
    }    
}