animation using css

.wrapper {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh
}

.pulse {
    width: 70px;
    height: 70px;
    background-color: red;
    border-radius: 50%;
    position: relative;
    animation: animate 3s linear infinite
}

body{
background-color: purple;
}

@keyframes party{
    0% {background-color: red;}
    10% {background-color: orange;}
    20% {background-color: yellow;}
    30% {background-color: green;}
    40% {background-color: blue;}
    50% {background-color: purple;} 
}

@-webkit-keyframes party{
    0% {background-color: red;}
    10% {background-color: orange;}
    20% {background-color: yellow;}
    30% {background-color: green;}
    40% {background-color: blue;}
    50% {background-color: purple;} 
}

@keyframes animatedBackground {
  from {
    background-position: 0 0;
  }
  to {
    background-position: 100% 0;
  }
}
#animate-area {
  width: 200px;
  height: 200px;
  background-image: url(http://placekitten.com/400/200);
  background-position: 0px 0px;
  background-repeat: repeat-x;
  animation: animatedBackground 10s linear infinite alternate;
}

function party(){
  document.body.style.animation = 'party 2.5s infinite linear';
}