galaxy/Buttons/Cornerstone-04_helpless-cheetah-32.html

<button><span>Hover</span></button>
<style>
/* From Uiverse.io by Cornerstone-04 - Tags: button */
button {
  cursor: pointer;
  background: transparent;
  position: relative;
  display: inline-block;
  padding: 15px 30px;
  outline: none;
  border: 2px solid #0f0;
  margin: 40px;
  width: 150px;
  height: 60px;
  text-transform: uppercase;
  font-weight: 900;
  text-decoration: none;
  letter-spacing: 2px;
  color: #fff;
  -webkit-box-reflect: below 0px linear-gradient(transparent, #0002);
  transition: 0.45s;
  transition-delay: 0s;
}

button:hover {
  transition-delay: 1.5s;
  color: #000;
  box-shadow: 0 0 10px #0f0,
                0 0 20px #0f0,
                0 0 40px #0f0, 
                0 0 80px #0f0, 
                0 0 100px #0f0;
}

button span {
  position: relative;
  z-index: 100;
}

button::before {
  content: "";
  position: absolute;
  left: -20px;
  top: 50%;
  transform: translateY(-50%);
  width: 20px;
  height: 2px;
  background: #0f0;
  box-shadow: 5px -8px 0 #0f0, 
              5px 8px 0 #0f0;
  transition: width 0.5s, 
              left 0.5s, 
              height 0.5s, 
              box-shadow 0.5s;
  transition-delay: 1s, 0.5s, 0s, 0s;
}

button:hover::before {
  width: 60%;
  height: 100%;
  /* right: -2px; */
  left: -2px;
  box-shadow: 5px 0 0 #0f0, 
              5px 0 0 #0f0;
  transition-delay: 0s, 0.5s, 1s, 1s;
}

button::after {
  content: "";
  position: absolute;
  right: -20px;
  top: 50%;
  transform: translateY(-50%);
  width: 20px;
  height: 2px;
  background: #0f0;
  box-shadow: -5px -8px 0 #0f0, 
              -5px 8px 0 #0f0;
  transition: width 0.5s, right 0.5s, height 0.5s, box-shadow 0.5s;
  transition-delay: 1s, 0.5s, 0s, 0s;
}

button:hover::after {
  width: 60%;
  height: 102%;
  right: -2px;
  box-shadow: -5px 0 0 #0f0, -5px 0 0 #0f0;
  transition-delay: 0s, 0.5s, 1s, 1s;
}

</style>