//Specify affected tags. Add or remove from list:
var tgs = new Array( 'td','tr','p','h3','h4');

//Specify spectrum of different font sizes:
//var szs = new Array( 'xx-small','x-small','small','medium','large','x-large','xx-large' );
var szs = new Array( '12px','14px','16px' );
var startSz = 0;

function ts( trgt,inc ) {
if (!document.getElementById) return
var d = document,cEl = null,sz = startSz,i,j,cTags;

sz=inc;
//sz += inc;
//if ( sz < 0 ) sz = 0;
//if ( sz > 2 ) sz = 2;
//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 ];
}
}