body {
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  justify-content: space-evenly;
  align-items: center;
  min-height: 100vh;
  font-family: consolas;
  background-color: #031321;
}
a {
  text-decoration: none;
  font-size: 1.5em;
  color: #2196f3;
  letter-spacing: 4px;
  padding: 1em 1.5em;
  transition: 0.2s;
  position: relative;
  display: inline-block;
  text-transform: uppercase;
  overflow: hidden;
}
a:hover {
  background-color: #2196f3;
  color: #255784;
  transition-delay: 500ms;
  box-shadow: 0 0 10px #2196f3, 0 0 40px #2196f3, 0 0 80px #2196f3;
}
a span {
  position: absolute;
  display: block;
}
a span:nth-child(1) {
  top: 0;
  left: -100%;
  height: 2px;
  width: 100%;
  background: linear-gradient(90deg, transparent, #2196f3);
}
a:hover span:nth-child(1) {
  left: 100%;
  transition: 500ms;
}
a span:nth-child(2) {
  right: 0;
  top: -100%;
  height: 100%;
  width: 2px;
  background: linear-gradient(180deg, transparent, #2196f3);
}
a:hover span:nth-child(2) {
  top: 100%;
  transition: 500ms;
  transition-delay: 125ms;
}
a span:nth-child(3) {
  bottom: 0;
  right: -100%;
  height: 2px;
  width: 100%;
  background: linear-gradient(270deg, transparent, #2196f3);
}
a:hover span:nth-child(3) {
  right: 100%;
  transition: 500ms;
  transition-delay: 250ms;
}
a span:nth-child(4) {
  left: 0;
  bottom: -100%;
  height: 100%;
  width: 2px;
  background: linear-gradient(360deg, transparent, #2196f3);
}
a:hover span:nth-child(4) {
  bottom: 100%;
  transition: 500ms;
  transition-delay: 375ms;
}
body a:nth-child(2) {
  filter: hue-rotate(90deg);
}
body a:nth-child(3) {
  filter: hue-rotate(270deg);
}