Taken from https://sumtips.com/tips-n-tricks/make-any-site-do-a-barrel-roll/

barrel-roll.css

@-webkit-keyframes roll {
  from { -webkit-transform: rotate(0deg) }
  to { -webkit-transform: rotate(360deg) }
}

@-moz-keyframes roll {
  from { -moz-transform: rotate(0deg) }
  to { -moz-transform: rotate(360deg) }
}

@keyframes roll {
  from { transform: rotate(0deg) }
  to { transform: rotate(360deg) }
}

body {
  -moz-animation-name: roll;
  -moz-animation-duration: 4s;
  -moz-animation-iteration-count: 1;
  -webkit-animation-name: roll;
  -webkit-animation-duration: 4s;
  -webkit-animation-iteration-count: 1;
}