On my page.php I have 3 buttons :
<input type="submit" value="Btn 1"  id="btn1">   
<input type="submit" value="Btn 2" id="btn2" onClick="action();>  
<input type="submit" value="Btn 3" id="btn3" onClick="action();>  
first Btn 1 button hidden with load:
document.getElementById('btn1').style.visibility = 'hidden';
with click on Btn 2 or Btn 3 I want hide Btn 2 or Btn 3 and show Btn 1:
var hidden = false;
    function action() {
        hidden = !hidden;
        if(hidden) {
            document.getElementById('btn1').style.visibility = 'visible';
            document.getElementById('btn2').style.visibility = 'hidden';
            document.getElementById('btn3').style.visibility = 'hidden';
        } 
    }
this way hidden button Btn 1 leaves empty space in place where it was visible, or if I put it below Btn 2 and Btn 3 then I got two empty spaces in places of Btn 2 and Btn 3.  
How it is possible show and hide buttons in same place on html page  
