style.css

* {
  margin: 0%;
  padding: 0%;
  box-sizing: border-box;
}
html {
  font-size: 62.5%;
}

h1 {
  font-family: "Poppins", sans-serif;
  color: rgb(127, 146, 255);
}

.main_header {
  width: 100vw;
  height: 100vh;
  background: #0b1522;
  display: grid;
  place-items: center;
}
.center-div {
  width: 10rem;
  height: 10rem;
  background-color: #f20044;
  position: relative;
  transform: rotate(45deg);
  box-shadow: -10px 10px 90px #f20044;
  animation: hbeat 1s linear infinite;
}
.center-div::before {
  content: "";
  width: 100%;
  height: 100%;
  background-color: #f20044;
  position: absolute;
  border-radius: 50%;
  transform: translateY(-50%);
  box-shadow: -10px -10px 90px #f20044;
}
.center-div::after {
  content: "";
  width: 100%;
  height: 100%;
  background-color: #f20044;
  position: absolute;
  border-radius: 50%;
  transform: translateX(-50%);
  box-shadow: 10px 10px 90px #f20044;
}
@keyframes hbeat {
  0% {
    transform: rotate(45deg) scale(1);
  }
  20% {
    transform: rotate(45deg) scale(1);
  }
  40% {
    transform: rotate(45deg) scale(1.4);
  }
  60% {
    transform: rotate(45deg) scale(1.2);
  }
  80% {
    transform: rotate(45deg) scale(1.4);
  }
  100% {
    transform: rotate(45deg) scale(1);
  }
}