var unit = "px";
var totalChange = 0;
var rules;

function increaseFontSize() {
    ts('body', 1);
}

function decreaseFontSize() {
    ts('body', -1);
}

function resetFontSize()
{
    ts('body', totalChange);
}

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

//Specify spectrum of different font sizes:
var szs = new Array( 'xx-small','x-small','small','medium','large','x-large','xx-large' );
var startSz = 2;

function ts( trgt,inc ) {
	if (!document.getElementById) return
	var d = document,cEl = null,sz = startSz,i,j,cTags;
	
	sz += inc;
	totalChange -= inc;
	
	if ( sz < 0 ) 
	{
	    sz = 0;
	    totalChange = 2;
	}
	if ( sz > 6 ) 
	{
	    sz = 6;
	    totalChange = -4;
	}
	startSz = sz;
		
	if ( !( cEl = d.getElementById( trgt ) ) ) cEl = d.getElementsByTagName( trgt )[ 0 ];

	cEl.style.fontSize = szs[ sz ];

	for ( i = 0 ; i < tgs.length ; i++ ) {
		cTags = cEl.getElementsByTagName( tgs[ i ] );
		for ( j = 0 ; j < cTags.length ; j++ ) cTags[ j ].style.fontSize = szs[ sz ];
	}
}