The stylesheet sharing.css isn't loading.
<link rel='stylesheet' id='sharedaddy-css' href='http://YOUR DOMAIN/wp-content/plugins/jetpack/modules/sharedaddy/sharing.css?ver=2.3.1' type='text/css' media='all' />
When I clicked the full URL in page source - it reloads the source code instead of opening the stylesheet.
When pasting the stylesheet URL in a blank window - it loads the front page of your site. It should send a 404 page not found error if it can't find the file.
I can load the stylesheet if I remove the ver=2.3.1 from the URL
From other tests I could do it looks like you're using a redirect plugin in automatic mode - possibly 404 Redirected???
Trying other partial broken-link URLs - (you'll see them in the logs) opens the best-match page - instead of a 404 not found return
Try turning off any redirect plugins, and see if that fixes the error.
404 Redirected does a lot of strange things in Automatic (I use it for all the WP sites I manage - never in auto mode).
Let's know if this helps?