Gradient & border opacity

Gradient & border opacity

by Csaba Hellinger

HTML

<button class="default">Default</button>
<button class="disabled">Disabled</button>

CSS

button {
  --border-width: 5px;
  position: relative;
  background-clip: padding-box;
  &::before {
    content: '';
    position: absolute;
    inset: 0;
    z-index: -1;
    margin: calc(-1 * var(--border-width));
    border-radius: inherit; 
  }
}

.default {
  background: linear-gradient(90deg, #8df, #008) padding-box;
  border: solid var(--border-width) transparent;
  &::before {
    background: linear-gradient(90deg, #ff0, #f00);
  }
}

.disabled {
  background: linear-gradient(90deg, #8dfb, #008b) padding-box;
  border: solid var(--border-width) transparent;
  &::before {
    background: linear-gradient(90deg, #ff0b, #f00b);
  }
}

/* just for the demo */

body {
  background: #222;
  background: url(https://upload.wikimedia.org/wikipedia/commons/thumb/7/70/Checkerboard_pattern.svg/480px-Checkerboard_pattern.svg.png) repeat;
  background-size: 10%;
  margin: 2rem;
}

button {
  font-size: 2rem;
  color: yellow;
  border-radius: 999rem;
  padding: 1rem;
}