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

//Specify spectrum of different font sizes:
var szs = new Array('','','11px','12px','13px','14px','xx-large');


/* '1.4em','1.3em','1.2em','1.1em','1.2em','1.3em','1.4em' */

/* '12px','13px','14px','11px','12px','13px','14px' */

var startSz = 1;

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 > 5 ) sz = 5;
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 ];
}
}