It looks like it's simply checking to see if CSS is being inlined in responses. The page source is pretty simple, and it looks like it's doing everything on th

It looks like it's simply checking to see if CSS is being inlined in responses. The page source is pretty simple, and it looks like it's doing everything on the client side. A CSS file is being included as the first link in the HEAD, and then JavaScript looks at the URL of the first link to see if it's the same as what it expects.