Starburst Thinking Mark: CSS AI Animation

Starburst Thinking Mark

An eight ray starburst whose rays stretch and settle in a wave that runs around the circle while the mark slowly turns, next to a muted Pondering label. Rays are rotated spans, no SVG.

Also known as: ai thinking loading animation, claude thinking animation, asterisk spinner, starburst loader.

Pondering…

Color Base size 16px Dark background

HTML

<div class="aia-starburst-thinking" role="status" aria-label="Thinking">
  <span class="aia-starburst-thinking-mark" aria-hidden="true"><i style="--i: 0"></i><i style="--i: 1"></i><i style="--i: 2"></i><i style="--i: 3"></i><i style="--i: 4"></i><i style="--i: 5"></i><i style="--i: 6"></i><i style="--i: 7"></i></span>
  <span class="aia-starburst-thinking-label">Pondering…</span>
</div>

CSS

.aia-starburst-thinking {
  --c: var(--aia-color, #7c5cff);
  font-size: var(--aia-size, 16px);
  font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
  line-height: 1.4;
  display: inline-flex;
  align-items: center;
  gap: 0.75em;
}
.aia-starburst-thinking-mark {
  position: relative;
  width: 2.8em;
  height: 2.8em;
  animation: aia-starburst-thinking-turn 14s linear infinite;
}
.aia-starburst-thinking-mark i {
  position: absolute;
  left: calc(50% - 0.12em);
  top: 0;
  width: 0.24em;
  height: 50%;
  transform-origin: 50% 100%;
  transform: rotate(calc(var(--i) * 45deg));
}
.aia-starburst-thinking-mark i::before {
  content: "";
  position: absolute;
  inset: 0 0 34% 0;
  border-radius: 1em;
  background: var(--c);
  transform-origin: 50% 100%;
  animation: aia-starburst-thinking-ray 1.6s cubic-bezier(0.45, 0, 0.55, 1) infinite;
  animation-delay: calc(var(--i) * -0.2s);
}
.aia-starburst-thinking-mark i:nth-child(even)::before {
  inset: 14% 8% 34% 8%;
  background: color-mix(in srgb, var(--c) 70%, #fff);
}
.aia-starburst-thinking-label {
  font-size: 1.35em;
  font-weight: 500;
  color: color-mix(in srgb, currentColor 62%, transparent);
}
@keyframes aia-starburst-thinking-turn {
  to { transform: rotate(360deg); }
}
@keyframes aia-starburst-thinking-ray {
  0%, 100% { transform: scaleY(0.4); opacity: 0.55; }
  50%      { transform: scaleY(1); opacity: 1; }
}
@media (prefers-reduced-motion: reduce) {
  .aia-starburst-thinking-mark,
  .aia-starburst-thinking-mark i::before { animation: none; }
  .aia-starburst-thinking-mark i::before { transform: scaleY(0.8); }
}

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

Customizing this snippet

Color: set --aia-color on the element or a parent. Currently previewing #3b82f6.
Base size: set --aia-size. Every other dimension is in em, so the whole thing scales together. Currently previewing 16px.
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.

Starburst Thinking Mark

HTML

CSS

Customizing this snippet

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