import Masonry from 'masonry-layout';

var elem = document.querySelector('.masonry');
var msnry = new Masonry( elem, {
  itemSelector: '.col-md-6'
});

@@ -139,13 +139,39 @@
 ol-md-6'
+,%0A  percentPosition: true,
 %0A%7D);%0A

add use of percentage in masonry options