.btn {
  font-size: 50px;
  color: #222;
  font-family: inherit;
  font-weight: 800;
  cursor: pointer;
  position: relative;
  border: none;
  background: none;
  text-transform: uppercase;
  transition-timing-function: cubic-bezier(0.25, 0.8, 0.25, 1);
  transition-duration: 500ms;
  transition-property: color;
}

.btn:focus,
.btn:hover {
  transition-duration: 500ms;
  color: #222222aa;
  background: linear-gradient(0, #0f0, #000 70%, #000 99%);
  background-clip: text;
  -webkit-background-clip: text;
}

.btn:focus:after,
.btn:hover:after {
  width: 100%;
  left: 0px;
}

.btn:after {
  content: "";
  pointer-events: none;
  bottom: -2px;
  left: 0px;
  position: absolute;
  width: 0%;
  height: 5px;
  background-color: #dfffdf;
  transition-timing-function: cubic-bezier(0.25, 0.8, 0.25, 1);
  transition-duration: 500ms;
  transition-property: width, left;
}

.btn:focus:before,
.btn:hover:before {
  width: 100%;
  left: 0px;
}

.btn:before {
  content: "";
  pointer-events: none;
  bottom: -2px;
  left: 0px;
  position: absolute;
  width: 0%;
  height: 5px;
  background-color: #0f0;
  transition-timing-function: cubic-bezier(0.25, 0.8, 0.25, 1);
  transition-duration: 500ms;
  transition-property: width, left;
  filter: blur(5px);
}