$(window).load(function () {
  var maxHeight;
  maxHeight=0; 
  $(".fohir_doboz").each(
    function () {
      if (this.offsetHeight > maxHeight) {
        maxHeight=this.offsetHeight;
      }
    } 
  );
  maxHeight += 10;
  $(".fohir_doboz").each(
    function () {
      $(this).css({height: maxHeight, visibility: 'visible'});
    }
  );
  $("#fohirek").css("height",maxHeight);
});