document.getElementById("nav").innerHTML += '<span id="MyEdit" style="position:absolute;top:0;left:0"></span>';
document.getElementById("MyEdit").innerHTML = '<input  id="g3_s" onclick="fun()" type="button" value="Ukryj" style="position:fixed;margin-left:3px;margin-top:3px"/>'

function fun(){
var blok  = document.getElementsByClassName('comments-stream ')[0];
var warunek = blok.getElementsByClassName('wblock lcontrast dC').length;
var elem = new Array();
elem   = blok.getElementsByClassName('wblock lcontrast dC');
var klasa = "color-0 showProfileSummary";

for(var i = 0;i<warunek;i++){
	var czy=elem[i].getElementsByClassName(klasa);
if (czy.length!==0) {
   blok.getElementsByClassName('wblock lcontrast dC')[i].innerHTML="";
   blok.getElementsByClassName('wblock lcontrast dC')[i].style.height = "0px!important";
}}
}