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

//Specify spectrum of different font sizes:
  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 ];
    }
  }