<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" http-equiv="X-UA-Compatible" content="IE=edge" />
    <style>
        .loader {
            border: 6px solid #f3f3f3;
            border-radius: 50%;
            border-top: 6px solid #3498db;
            width: 40px;
            height: 40px;
            -webkit-animation: spin 1s linear infinite; /* Safari */
            animation: spin 1s linear infinite;
            position: absolute;
            top: 50%;
            left: 50%;
            mar