I waited for a few minutes and nothing happened. Don't know if the creator knows about this thread, but I checked the console, and saw the below error. I'm pretty sure the issue is that I have the HttpsEverywhere plugin installed, and this link is hardcoded to be insecure. I think if the source was changed to "//" instead of "http://" this would work.

Mixed Content: The page at 'https://garris.github.io/TremulaJS/' was loaded over HTTPS, but requested an insecure XMLHttpRequest endpoint 'http://ws-decor.art.com/api/decorProductSearch?engine=judy&p.... This request has been blocked; the content must be served over HTTPS.

I had the same issue. IN my case I had https everywhere addon installed. That forces https.

I don't think waiting is going to fix this problem...

    XMLHttpRequest cannot load http://ws-decor.art.com/api/decorProductSearch?engine=judy&pageNumber=1&num…se&totalRetrieved=0&getDataFromThisUrl=null&totalFound=1000&pageReturned=4.
    No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://garris.github.io' is therefore not allowed access.

In my case it was the privacy badger plugin blocking calls to art.com, where the images are from.

I had the same experience (a grey page with not much on it), it could use a loading bar.