Why won't my window lock: Javascript?

programming web dev
1

This is my code for opening a new window as a certain size:

function OpenPage(theURL){
	var width = screen.width
	var height = screen.height
	if (width <= 900)
	{
	window.open(theURL, '', 'fullscreen=yes, scrollbars=no, resizable=no');
	}
	else
	{
	window.open(theURL,'','width=970,height=584,status=no,menubar=no,scrollbars=no,resizable=no')
	}
}
</SCRIPT>

It opens the window fine and etc BUT for some reason I can still resize it even though I put the code resizable = no. Can anyone see why?

Thanks for any help!