Merge pull request #64 from ophian/patch-1

added 	  if (nh < 1) { var nh = 0; }

Fixes #1813

lib/gallery.common.js

@@ -33,6 +33,7 @@
       var elh = $(el).height();
       var ph = $(this).height();
       var nh = (ph - elh) / 2;
+      if (nh < 1) { var nh = 0; }
       $(el).css('margin-top', nh);
     });
   };