var ofs=0;
function charSize(act)
{	var sht, allshts, rul, allruls, udone, sfs, nfs;
	allshts=document.styleSheets;
	udone=false;
	for (var is=0;is<allshts.length;is++)
		{	sht=allshts[is];
			allruls=sht.cssRules ? sht.cssRules : sht.rules;
			for (var ir=0; ir<allruls.length; ir++)
				{	rul=allruls[ir];
					if (rul.selectorText.toLowerCase()==".testo_articoli")
					{	sfs=rul.style.fontSize;
						nfs= parseInt(sfs.replace("px",""));
						if (ofs==0) ofs=nfs;
						if (act==0) nfs=ofs;
						if (act>0) nfs+=1;
						if (act<0) nfs-=1;
						rul.style.fontSize=nfs+"px";
						udone=true;
						break;
					}
				}
			if (udone) break;
		}
}