*,
*::after,
*::before{
   box-sizing: border-box;
}
body{
   margin: 0;
   padding: 0;
   min-height: 100vh;
   height: auto;
   display: flex;
   align-items: center;
   justify-content: center;
   background: #333;
}
.loader{
   display: inline-block;
   font-size: 24px;
   color: #fff;
   position: relative;
   animation: rotation 0.5s linear infinite;
} 

@keyframes rotation{
   0%{
      transform: scale(1);
   }
   50%{
      transform: scale(2);
   }
   100%{
      transform: scale(1);
   }
}