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

//Specify spectrum of different font sizes:
var szs = 11;
var startSz = 2;

function ts( trgt,inc ) {
	if (!document.getElementById) return
	var d = document,cEl = null,sz = startSz,i,j,cTags;
	
	sz += inc;
	if ( sz < 0 ) sz = 0;
	if ( sz > 6 ) sz = 6;
	startSz = sz;
		
	if ( !( cEl = d.getElementById( trgt ) ) ) cEl = d.getElementsByTagName( trgt )[ 0 ];
	
	if(szs>=16)
		szs=15;
		
	if(szs<=10)
		szs=10;
	if(inc=='-')
		szs=szs-1;
	else
		szs=szs+1;
		
	cEl.style.fontSize =szs+'px';
	for ( i = 0 ; i < tgs.length ; i++ ) {
		cTags = cEl.getElementsByTagName( tgs[ i ] );
		for ( j = 0 ; j < cTags.length ; j++ ) cTags[ j ].style.fontSize =szs+'px';;
	}
}