body {
  background-color: #25272c;
  display: grid;
  place-items: center;
  height: 100vh;
}

.container {
  background: #eb5bec;
  border-radius: 16px;
  display: grid;
  height: 385px;
  overflow: hidden;
  place-items: center;
  position: relative;
  width: 315px;
}

.box {
  animation: grow 10s linear infinite;
  background: #471e45;
  height: 100px;
  opacity: 0.5;
  position: absolute;
  width: 100px;
}

@keyframes grow {
  from {
    opacity: 0.5;
    transform: scale(0);
  }
  to {
    opacity: 0;
    transform: scale(3.85);
  }
}