function draw() {
  var bg = document.getElementById('bg'),
      width = document.documentElement.clientWidth,
      height = document.documentElement.clientHeight,
      ctx, radgrad, offset;
  if (! bg.getContext) { return; }
  bg.setAttribute('width', width);
  bg.setAttribute('height', height);
  if (typeof G_vmlCanvasManager != "undefined") {
    offset = 0.1;               // IE
  } else {
    offset = 0.5;               // Firefox, Opera, Chrome, etc.
  }
  ctx = bg.getContext('2d');
  radgrad = ctx.createRadialGradient(0, 0, 0, 0, -1 * (height/2), width);
  radgrad.addColorStop(0, 'rgba(255,255,255,1)');
  radgrad.addColorStop(offset, 'rgba(255,255,255,0.3)');
  radgrad.addColorStop(1, 'rgba(58,110,165,1)');
  ctx.fillStyle = radgrad;
  ctx.fillRect(0, 0, width, height);
}
window.onload = function () { draw(); }
window.onresize = function () { draw(); }