video { 
     position: fixed;
     top: 50%;
     left: 50%;
     min-width: 100%;
     min-height: 100%;
     width: auto;
     height: auto;
     z-index: -100;
     transform: translateX(-50%) translateY(-50%);
  background: no-repeat;
   background-size: cover;
   transition: 1s opacity;
 }