body {
      animation: colorchange 50s; /* animation-name followed by duration in seconds*/
         /* you could also use milliseconds (ms) or something like 2.5s */
      -webkit-animation: colorchange 50s; /* Chrome and Safari */
    }

    @keyframes colorchange
    {
      0%   {background: #0664d2;}
      25%  {background: #ff364f;}
      50%  {background: #e61796;}
      75%  {background: #00ffb0;}
      100% {background: #0664d2;}
    }

    @-webkit-keyframes colorchange /* Safari and Chrome - necessary duplicate */
    {
      0%   {background: #0664d2;}
      25%  {background: #ff364f;}
      50%  {background: #e61796;}
      75%  {background: #00ffb;}
      100% {background: #0664d2;}
    }