The errors it gives are
Content wider than screen
Which is confusing because I don’t see any horizontal scroll bars in RWD view 320px.
and
Links too close together
Which is probably the social icons at the top.
It also took quite a long time and gave this warning:-
A temporary error occurred. 17 resources on this page could not be
loaded. The results and screenshot may be incorrect. You may want to try
again later.