envbg.js

<script>
  (function() {
    var body = document.getElementsByTagName("body")[0];
    var canvas = document.createElement("canvas");
    var ctx = canvas.getContext("2d");

    canvas.width = 400;
    canvas.height = 250;
    ctx.font = "bold 48px sans-serif";
    ctx.fillStyle = "rgba(0, 0, 0, 0.1)";
    ctx.rotate(30 * Math.PI / 180);
    ctx.textBaseline = "middle";
    ctx.fillText("development", 30, 30);

    body.style.backgroundImage = "url("+canvas.toDataURL()+")";
  })();
</script>