var cambiataglia = {
  sizeUnit: "px",
  defaultSize: 10,
  maxSize:     20,
  minSize:     6,

  inizio: function() {
    if ( !document.getElementById || !document.getElementsByTagName ) return;
    var size = window.location.search? window.location.search.slice(1): getCucca("fontSize");
    size = !isNaN( parseFloat(size) )? parseFloat(size): this.defaultSize;
    if ( size > this.maxSize || size < this.minSize ) size = this.defaultSize;
    var cnt = document.getElementsByTagName("table");
    for(i=0; i<cnt.length; i++) {
    document.getElementsByTagName("table")[i].style.fontSize = size + this.sizeUnit;
    }
  },
  
  aggiusta: function(inc) {
    var size = parseFloat( document.getElementsByTagName("table")[0].style.fontSize );
    size += inc;
    if (inc > 0) size = Math.min(size, this.maxSize);
    else size = Math.max(size, this.minSize);
    setCucca( "fontSize", size, 180, "/" );
    var cnt = document.getElementsByTagName("table");
    for(i=0; i<cnt.length; i++) {
    document.getElementsByTagName("table")[i].style.fontSize = size + this.sizeUnit;
    }
  }, 

  ripristina: function() {
    var cnt = document.getElementsByTagName("table");
    for(i=0; i<cnt.length; i++) {
    document.getElementsByTagName("table")[i].style.fontSize = this.defaultSize + this.sizeUnit;
  } 
    deleteCucca("fontSize", "/");
  }
  
}

cambiataglia.inizio();