Im trying to do the same button but without the need to make hover (running the animated background all the time).

I've tried different approach like using background-clip, shadows, etc but unfortunately without success.

Maybe if I use another element like a div and span can work but I really want to do it with a button.

Codepen

html,
body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100vh;
  display: flex;
  flex-direction: row;
  justify-content: center;
  align-items: center;
  background: #000;
}

.glow-on-hover {
  width: 220px;
  height: 50px;
  border: none;
  outline: none;
  color: #fff;
  background: #111;
  cursor: pointer;
  position: relative;
  z-index: 0;
  border-radius: 10px;
}

.glow-on-hover:before {
  content: '';
  background: linear-gradient(45deg, #ff0000, #ff7300, #fffb00, #48ff00, #00ffd5, #002bff, #7a00ff, #ff00c8, #ff0000);
  position: absolute;
  top: -2px;
  left: -2px;
  background-size: 400%;
  z-index: -1;
  filter: blur(5px);
  width: calc(100%   4px);
  height: calc(100%   4px);
  animation: glowing 20s linear infinite;
  opacity: 0;
  transition: opacity .3s ease-in-out;
  border-radius: 10px;
}

.glow-on-hover:active {
  color: #000
}

.glow-on-hover:active:after {
  background: transparent;
}

.glow-on-hover:hover:before {
  opacity: 1;
}

.glow-on-hover:after {
  z-index: -1;
  content: '';
  position: absolute;
  width: 100%;
  height: 100%;
  background: #111;
  left: 0;
  top: 0;
  border-radius: 10px;
}

@keyframes glowing {
  0% {
    background-position: 0 0;
  }
  50% {
    background-position: 400% 0;
  }
  100% {
    background-position: 0 0;
  }
}

<link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet">
<button class="glow-on-hover" type="button">HOVER ME, THEN CLICK ME!</button>

<iframe name="sif1" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

CodePudding user response：

What is making your ::before pseudo-element to hide when it's not hovered is opacity:0. If you remove it, you will have the desired effect. Also, you might want to remove the glow-on-hover:hover:before selector since it's not going to be any use.