{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

section {
  position: relative;
  width: 100%;
  height: 100%;
  background-color: #001300;
  display: flex;
  flex-wrap: wrap;
  overflow: hidden;
  animation: changeColor 15s linear infinite;
}
@keyframes changeColor {
  0% {
    filter: hue-rotate(0deg);
  }
  100% {
    filter: hue-rotate(360deg);
  }
}
span {
  position: relative;
  width: 40px;
  height: 40px;
  display: block;
}
span::before {
  content: " ";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: #00ff0a;
  transform: scale(0.1);
  box-shadow: 0 0 10px #00ff0a,
    0 0 20px #00ff0a 0 0 40px #00ff0a 0 0 60px #00ff0a 0 0 80px #00ff0a 0 0
      100px #00ff0a;
  border-radius: 50%;
  pointer-events: none;
  transition: 2s;
}
span:hover::before {
  transform: scale(0.4);
  transition: 0s;
}

* {
  box-sizing: border-box;
}