html {
  background-color: #efebe9; 
}

body {
  background-color: #ef5350;
  height: 300px;
  width: 300px;
  position: absolute; 
  top: 40%; 
  left: 50%; 
  transform: rotate(45deg) translateX(-50%);
}

body:before,
body:after {
  content: "";
  border-radius: 50%;
  height: 300px;
  position: absolute;
  width: 300px;
}

body:before {
  top: 0;
  left: -146px;
  background-color: #ef5350; 
}

body:after {
  background-color: #ef5350;
  top: -146px;
  left: 0;
}

body {
  transform: rotate(45deg) translateX(-50%);
  animation: beat 1s infinite;
}

@keyframes beat {
  0% {
    transform: rotate(45deg) translateX(-50%) scale( .75 );
  }
  20% {
    transform: rotate(45deg) translateX(-50%) scale( 1 );
  }
  40% {
    transform: rotate(45deg) translateX(-50%) scale( .75 );
  }
  60% {
    transform: rotate(45deg) translateX(-50%) scale( 1 );
  }
  80% {
    transform: rotate(45deg) translateX(-50%) scale( .75 );
  }
  100% {
    transform: rotate(45deg) translateX(-50%) scale( .75 );
  }
}