d3 first svg

Working though the Frontend Masters d3js series. Built with blockbuilder.org

d3js data bind using reddit/r/pics.json as data.
This works in blockbuilder but not in bl.ocks.org, why?

forked from hsuttong's block: d3 first transition

<!DOCTYPE html>
<head>
  <meta charset="utf-8"> 
  <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.9/d3.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
    svg { width: 100%; height: 100%; }
  </style>
</head>
<body>
  <script>
    var margin = {top: 14, right: 10, bottom: 20, left: 10};
    var width = 960 - margin.left - margin.right;
    var height = 500 - margin.top - margin.bottom;
   
    var svg = d3.select("body").append("svg")
    	.attr("width", width + margin.left + margin.right)
    	.attr("height", height + margin.top + margin.bottom)
    	.attr("transform", "translate(" + margin.left + "," + margin.top + ")");

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.9/d3.min.js