<style>
  @-webkit-keyframes argh-my-eyes {
    0%   { background-color: #53fa20; }
    49% { background-color: #53fa20; }
    50% { background-color: #3ab017; }
    99% { background-color: #3ab017; }
    100% { background-color: #53fa20; }
  }
  @-moz-keyframes argh-my-eyes {
    0%   { background-color: #53fa20; }
    49% { background-color: #53fa20; }
    50% { background-color: #3ab017; }
    99% { background-color: #3ab017; }
    100% { background-color: #53fa20; }
  }
  @keyframes argh-my-eyes {
    0%   { background-color: #53fa20; }
    49% { background-color: #53fa20; }
    50% { background-color: #3ab017; }
    99% { background-color: #3ab017; }
    100% { background-color: #53fa20; }
  }
 body {
  -webkit-animation: argh-my-eyes 4s infinite;
  -moz-animation:    argh-my-eyes 4s infinite;
  animation:         argh-my-eyes 4s infinite;
}
</style>
