CSS code: rainbow start

body {
      animation: colorchange 1s; /* animation-name followed by duration in seconds*/
         /* you could also use milliseconds (ms) or something like 2.5s */
      -webkit-animation: colorchange 1s; /* Chrome and Safari */
    }



    @keyframes colorchange
    {
      0%   {background: red;}
      25%  {background: yellow;}
      50%  {background: blue;}
      75%  {background: green;}
      100% {background: red;}
    }


    @-webkit-keyframes colorchange /* Safari and Chrome - necessary duplicate */
    {
      0%   {background: red;}
      25%  {background: yellow;}
      50%  {background: blue;}
      75%  {background: green;}
      100% {background: red;}

{
 background-image: url("https://www.animatedimages.org/data/media/56/animated-computer-image-0254.gif");
 background-color: #cccccc;
}

#grad {
  background-image: radial-gradient(red, green, blue);
}