var tags = new Array('p','h2','div');
var pixelArray = new Array('11','12','14','16','18','19');
var initSize = 0;

function fontSizer(inc,unit) {
if (!document.getElementById)
return;
var size = initSize;
size += inc;
if (size < 0 ) {
size = 0;
}
if (size > 5 ) {
size = 5;
}
initSize = size;
getBody = document.getElementsByTagName('body')[0];
for (i = 0 ; i < tags.length ; i++ ) {
getallTags = getBody.getElementsByTagName(tags[i]);
for (k = 0 ; k < getallTags.length ; k++)
getallTags[k].style.fontSize = (unit=='px') ? pixelArray[size]+unit: emArray[size]+unit;
}
}