<div id='preloader'>
<div id='container' class='spinner'>
  <div id='loader'></div>  
</div>
</div>

#preloader{overflow:hidden;background:#00cec9;left:0;right:0;top:0;bottom:0;position:fixed;z-index:9999}
#container{width:70px;height:35px;overflow:hidden;position:absolute;top:calc(50% - 17px);left:calc(50% - 35px)}
#loader{width:70px;height:70px;border-style:solid;border-top-color:#FFF;border-right-color:#FFF;border-left-color:transparent;border-bottom-color:transparent;border-radius:50%;box-sizing:border-box;animation:rotate 3s ease-in-out infinite;transform:rotate(-200deg)}
@keyframes rotate{0%{border-width:10px}25%{border-width:3px}50%{transform:rotate(115deg);border-width:10px}75%{border-width:3px}100%{border-width:10px}}