//Specify affected tags. Add or remove from list:
var tgs = new Array( 'div','td','tr' );
var currentSize = 11;

function sizeMe(inc) {
	currentSize += inc;
	if (currentSize < 10) {
		currentSize = 10;	
	}
	if (currentSize > 14) {
		currentSize = 14;	
	}
	
	var daTags;
	
	for (i = 0; i < 2; i++) {
		daTags = document.body.getElementsByTagName( tgs[i] );
		for (j = 0; j < daTags.length; j++) {
			daTags[j].style.fontSize = currentSize + "px";	
		}
	}
}