var tgs = new Array( 'div','td','tr');
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;
  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.fontSize = szs[ sz ];
  }
}