colours.js

// http://colorbrewer2.org/
var colours = [[158,1,66],    [213,62,79],   [244,109,67],
               [253,174,97],  [254,224,139], [230,245,152],
               [171,221,164], [102,194,165], [50,136,189],
               [94,79,162]]

function rgba(color, alpha) {
  return 'rgba(' + color.concat(alpha).join(', ')  + ')'
}





var i = parseInt(id, 10)
document.body.style.backgroundColor = rgba(colours[i % (colours.length - 1)], 0.3)
document.body.style.backgroundColor = rgba(colours[i % (colours.length - 1)], 0.1)