In Chrome, when reducing the width of the window, the page collapses, but at a certain point (perhaps 500px or so) the entire page content simply disappears. There are no scrollbars or other features shown.

Oddly, this doesn't happen when the Developer tools window is shown.

Apart from the JS error about the missing code from yui.yahooapis.com, there are no other errors shown.

Increasing the width of the window restores the content.

The same behaviour doesn't appear in FF or IE10.