Border Beam Button: CSS Button Style & Animation

Border Beam Button

Two comets of light chase each other around the edge of a quiet outline button. Each is a soft dot moved along the rectangle with translate keyframes, then masked so only the border ring shows it.

Also known as: light traveling around border, border beam css, animated border light button.

Color Base size 18px Dark background Hold hover state

HTML

<button class="btn-border-beam" type="button">
  <span class="btn-border-beam-ring" aria-hidden="true"><i></i><i></i></span>
  View changelog
</button>

CSS

.btn-border-beam {
  --c: var(--btn-color, #3b82f6);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5em;
  padding: 0.75em 1.6em;
  border: 0;
  border-radius: 0.6em;
  font: 600 var(--btn-size, 18px)/1.1 system-ui, sans-serif;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  --w: 12em;
  --h: 3em;
  position: relative;
  width: var(--w);
  height: var(--h);
  padding: 0;
  border-radius: 0.8em;
  background: color-mix(in srgb, var(--c) 8%, transparent);
  color: var(--c);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--c) 28%, transparent);
  transition: background-color 0.25s ease, transform 0.2s ease;}
.btn-border-beam-ring {
  position: absolute;
  inset: 0;
  padding: 2px;
  border-radius: inherit;
  -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
  -webkit-mask-composite: xor;
  mask: linear-gradient(#000 0 0) content-box exclude, linear-gradient(#000 0 0);
  pointer-events: none;
}
.btn-border-beam-ring i {
  position: absolute;
  top: -3em;
  left: -3em;
  width: 6em;
  height: 6em;
  background: radial-gradient(closest-side, var(--c) 15%, transparent);
  animation: btn-border-beam-orbit 4s linear infinite;
}
.btn-border-beam-ring i:nth-child(2) {
  background: radial-gradient(closest-side, color-mix(in srgb, var(--c) 35%, #ec4899) 15%, transparent);
  animation-delay: -2s;
}
.btn-border-beam:is(:hover, :focus-visible) { background-color: color-mix(in srgb, var(--c) 14%, transparent); }
.btn-border-beam:active { transform: scale(0.97); }
@keyframes btn-border-beam-orbit {
  0%, 100% { transform: translate(0, 0); }
  40%      { transform: translate(var(--w), 0); }
  50%      { transform: translate(var(--w), var(--h)); }
  90%      { transform: translate(0, var(--h)); }
}

@media (prefers-reduced-motion: reduce) {
  .btn-border-beam, .btn-border-beam *, .btn-border-beam::before, .btn-border-beam::after, .btn-border-beam *::before, .btn-border-beam *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

Customizing this snippet

Color: set --btn-color on the element or a parent. Currently previewing #3b82f6.
Base size: set --btn-size. Every other dimension is in em, so the whole thing scales together. Currently previewing 18px.
Speed: change the duration on the transition or animation shorthand. Staggered delays are relative, so they keep their rhythm.
Reduced motion: the rule at the end of the CSS turns the motion off for people who asked their OS for less of it. Keep it.

Border Beam Button

HTML

CSS

Customizing this snippet

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