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

//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( '11','13','15');
//current font size
var currentSize=0;
function ts( trgt,inc ) {
    if(currentSize==inc)
        return;
    else
        currentSize=inc;
        
        
	if (!document.getElementById) return
	var d = document,cEl = null,i,j,cTags;
		
	if ( !( cEl = d.getElementById( trgt ) ) ) cEl = d.getElementsByTagName( trgt )[ 0 ];

	cEl.style.fontSize = szs[ inc ];

	for ( i = 0 ; i < tgs.length ; i++ ) {
		cTags = cEl.getElementsByTagName( tgs[ i ] );
		for ( j = 0 ; j < cTags.length ; j++ )
		{
		    cTags[ j ].style.fontSize = szs[ inc ];
		}
	}
}