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

//Specify spectrum of different font sizes:
var szs = new Array( '11px','14px','16px','18px','20px','22px');
var lht = new Array( '18px','21px','23px','25px','27px','29px');
var startSz = 0;

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 ];

	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.lineHeight = lht[ sz ]; 
     cTags[ j ].style.fontSize = szs[ sz ];
     }
	}
}