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HTML

              
                <div></div>
              
            
!

CSS

              
                // Motion Warning!

// Recreation of a Henning Lederer animated book cover
// http://blog.presentandcorrect.com/cover-stars-2
// There is most certainly a better way to do this! Just playing.

div
  width: 300px
  height: 300px
  animation: animate 600ms infinite linear
  @media (prefers-reduced-motion)
    animation: none

@keyframes animate
  from
    box-shadow: inset 0 5px 10px 5px alpha(black,.3),
                inset 0 0 0 0 tomato,
                inset 0 5px 10px 5px alpha(black,0),
                inset 0 0 0 20px tomato,
                inset 0 5px 10px 25px alpha(black,.3),
                inset 0 0 0 40px tomato,
                inset 0 5px 10px 45px alpha(black,.3),
                inset 0 0 0 60px tomato,
                inset 0 5px 10px 65px alpha(black,.3),
                inset 0 0 0 80px tomato,
                inset 0 5px 10px 85px alpha(black,.3),
                inset 0 0 0 100px tomato,
                inset 0 5px 10px 105px alpha(black,.3),
                inset 0 0 0 120px tomato,
                inset 0 5px 10px 125px alpha(black,.3),
                inset 0 0 0 140px tomato,
                inset 0 5px 10px 145px alpha(black,.3),
                inset 0 0 0 160px tomato
  to
    box-shadow: inset 0 5px 10px 5px alpha(black,.3),
                inset 0 0 0 20px tomato,
                inset 0 5px 10px 25px alpha(black,.3),
                inset 0 0 0 40px tomato,
                inset 0 5px 10px 45px alpha(black,.3),
                inset 0 0 0 60px tomato,
                inset 0 5px 10px 65px alpha(black,.3),
                inset 0 0 0 80px tomato,
                inset 0 5px 10px 85px alpha(black,.3),
                inset 0 0 0 100px tomato,
                inset 0 5px 10px 105px alpha(black,.3),
                inset 0 0 0 120px tomato,
                inset 0 5px 10px 125px alpha(black,.3),
                inset 0 0 0 140px tomato,
                inset 0 5px 10px 145px alpha(black,.3),
                inset 0 0 0 160px tomato,
                inset 0 5px 10px 165px alpha(black,.3),
                inset 0 0 0 180px tomato

body
  height: 100vh
  display: grid
  place-content: center
  background-color: tomato
              
            
!

JS

              
                // @lynnandtonic
// a.singlediv.com
              
            
!
999px

Console