var tgs = new Array( 'p' ); //pega todas as tags p//

//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];
        } 
    }
}