Artex / 500px Image Download

// ==UserScript==
// @name        500px Image Download
// @namespace   Groups
// @include    http://www.500px.com/*
// @match          *://*.500px.com/*
// @version     1.2
// @grant       none
// ==/UserScript==
window.addEventListener("DOMContentLoaded", function(){
	var image = document.getElementsByClassName("photo")[0];
    if (image) {
			var button = document.createElement("Button");
			button.type = "button";
			button.innerHTML = "Image Source";
			button.style.background = "transparent";
			button.style.border = "none";
			button.style.borderBottom = "1px solid #EEEFF2";
			button.style.padding = "15px 5px";
			button.style.color = "rgb(120, 120, 120)";
			button.style.width = "100%";
			var insertAt = document.getElementsByClassName("activity_region")[0];
			button = insertAt.parentNode.insertBefore(button, insertAt); //confused?

			button.onclick= function() {
				var winX = window.innerWidth;
				var winY = window.innerHeight;
				window.open(image.src, 'Download','height= width=');
			}
   }
}, false);