Actually I thought that was a poor example, coming from Google.
I haven’t looked at everything in detail but I did notice the internal script in the head tag.
It’s best practice to place your scripts right before the closing </body> tag, that way the page elements get loaded before the script runs.
I’m not positive, but I think library scripts like JQuery can go in the head.
EDIT:
You might find this responsive iframe to be of interest