<!DOCTYPE html>
<html>

<head>
  <style type='text/css'>
    html {
      width: 100%;
      height: 100%;
      background: rgba(0, 0, 0, 0);
    }

    .loader {
      position: absolute;
      top: 50%;
      left: 50%;
      width: 7.33333em;
      height: 7.33333em;
      margin-left: -3.66667em;
      margin-top: -3.66667em;
    }

    .loader-block {
      position: absolute;
      top: 0;
      left: 0;
      display: inline-block;
      opacity: 0;
      width: 2em;
      height: 2em;
      /* back