Eliminate render-blocking css in google page speed insights

[Dipak Ojha]

I am frustrating css rendering problem. According to Google PageSpeed Insights, My website speed is 71/100. I can remove almost error but I can't solve css rendering problem.

Your page has 1 blocking CSS resources. This causes a delay in rendering your page.

Actually my website has only one minified css file. When I search google, they suggest me to keep css files in head section and js files in above closing body tag, but it doesn't work. I try using all method and ideas which are found in google. Async or defer to js file doesn't work for me. Using noscript tag to css, css doesn't work. I try calling css from document.write function, still it doesn't work. I try removing inline css and all js file, but problem can't be solved. According to google page speed insights suggestion I include following code.

<script>
var cb = function() {
    var l = document.createElement('link'); l.rel = 'stylesheet';
    l.href = 'krishisansar.com/css/camera.min.css';
    var h = document.getElementsByTagName('head')[0]; h.parentNode.insertBefore(l, h);
  };
  var raf = requestAnimationFrame || mozRequestAnimationFrame ||
      webkitRequestAnimationFrame || msRequestAnimationFrame;
  if (raf) raf(cb);
  else window.addEventListener('load', cb);
</script>

but it is also helpless.

Many WordPress expert advice to use plugin, but my website doesn't use any platform like WP. I know, if I can fix this error, website speed will increase. How to fix this error ? Does css structure affect in this case ?