add check when acss is tried to open in codepen and add missing lib :P. fixes #100

src/dropdown.js

@@ -11,7 +11,7 @@
 		}
 	}
 	function init() {
-		var dropdowns = [].slice.call($all('[dropdown]'));
+		var dropdowns = $all('[dropdown]');
 		dropdowns.forEach(function (dropdown) {
 			dropdown.addEventListener('click', function (e) {
 				closeOpenDropdown(e.currentTarget);

src/script.js

@@ -1344,6 +1344,10 @@ runBtn, searchInput
 		});
 
 		codepenBtn.addEventListener('click', function (e) {
+			if (cssMode === CssModes.ACSS) {
+				alert('Oops! CodePen doesn\'t supports Atomic CSS currently.');
+				return;
+			}
 			var json = {
 				title: 'A Web Maker experiment',
 				html: scope.cm.html.getValue(),

src/style.css

@@ -657,7 +657,7 @@ li.CodeMirror-hint-active {
 }
 .dropdown__menu > li > a {
 	display: block;
-	padding: 10px 15px;
+	padding: 6px 15px;
 	color: #333;
 	cursor: pointer;
 }