//Specify affected tags. Add or remove from list:
var tgs = new Array( 'p','li','h3','h2','h4','pre','a','td','strong','b','font');

//Specify spectrum of different font sizes:
var szs = new Array( '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 > 3 ) sz = 3;
        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++ ) 
        		if (cTags[ j ].className != 'fixed') {
        			cTags[ j ].style.fontSize = szs[ sz ];
                	}
        }
}