Changing background colour of a Google Charts (Google Visualization) Graph

I'm trying to simply change the background color of a line graph I've created using Google Charts. I feel like I'm following Google's Official Documentation, but none of the changes I'm specifying are being applied.

I'm passing the options like so:

  var options = {
      backgroundColor: 'black',
      chartArea: {
                backgroundColor: 'black'
            },
      crosshair: {
          orientation: 'vertical'
      },
      animation: {
          startup: true,
          duration: 5000
      },
    width: 500,
    height: 300     
  }; 

But they are nearly all being ignored. See this JSFiddle for an example: http://ift.tt/1DvEcAv

I must be doing something really obvious wrong, but for the life of me I cannot figure out what.