AI CSS Animations

Checkpoint Rewind

A row of five checkpoints with a Now marker that rewinds two stops to Limiter, leaving the later ones dashed and hollow. Then each changed file flips to Restored or Removed and the count reaches 3/3.

Also known as: rewind agent checkpoint, restore code checkpoint, undo agent changes timeline.

Rewinding to checkpoint 3 Restored checkpoint 3
  • src/lib/limiter.tsModifiedRestored
  • src/routes/login.tsModifiedRestored
  • tests/lockout.test.tsAddedRemoved

HTML

<div class="aia-checkpoint-rewind" role="status" aria-label="Rewinding to checkpoint 3 and restoring files">
  <div class="aia-checkpoint-rewind-head">
    <span class="aia-checkpoint-rewind-title">
      <span class="aia-checkpoint-rewind-go"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="M4 12a8 8 0 1 0 2.4-5.7"/><path d="M4 4.5v4h4"/></svg>Rewinding to checkpoint 3</span>
      <span class="aia-checkpoint-rewind-done"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="m5.5 12.5 4 4 9-9.5"/></svg>Restored checkpoint 3</span>
    </span>
    <span class="aia-checkpoint-rewind-count" aria-hidden="true"></span>
  </div>
  <div class="aia-checkpoint-rewind-rail" aria-hidden="true">
    <span class="aia-checkpoint-rewind-line"></span>
    <span class="aia-checkpoint-rewind-cp"><i></i><em>Plan</em></span>
    <span class="aia-checkpoint-rewind-cp"><i></i><em>Schema</em></span>
    <span class="aia-checkpoint-rewind-cp"><i></i><em>Limiter</em></span>
    <span class="aia-checkpoint-rewind-cp"><i></i><em>Tests</em></span>
    <span class="aia-checkpoint-rewind-cp"><i></i><em>Refactor</em></span>
    <span class="aia-checkpoint-rewind-marker"></span>
  </div>
  <ul class="aia-checkpoint-rewind-files">
    <li><code>src/lib/limiter.ts</code><span class="aia-checkpoint-rewind-tag"><em>Modified</em><em>Restored</em></span></li>
    <li><code>src/routes/login.ts</code><span class="aia-checkpoint-rewind-tag"><em>Modified</em><em>Restored</em></span></li>
    <li><code>tests/lockout.test.ts</code><span class="aia-checkpoint-rewind-tag"><em>Added</em><em>Removed</em></span></li>
  </ul>
</div>

CSS

@property --aia-checkpoint-rewind-t {
  syntax: "<number>";
  inherits: true;
  initial-value: 0;
}
@property --aia-checkpoint-rewind-n {
  syntax: "<integer>";
  inherits: false;
  initial-value: 0;
}
.aia-checkpoint-rewind {
  --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;
  position: relative;
  box-sizing: border-box;
  padding: 0.9em 1em;
  border-radius: 0.9em;
  background: color-mix(in srgb, currentColor 3%, transparent);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, currentColor 11%, transparent), 0 0.1em 0.2em color-mix(in srgb, currentColor 4%, transparent), 0 0.9em 2em -1.1em rgb(0 0 0 / 0.3);
  --d: 8s;
  --t: var(--aia-checkpoint-rewind-t);
  --pos: calc(4 - clamp(0, var(--t), 1) * 2);
  --q: clamp(0, (var(--t) - 1.95) * 4, 1);
  width: 21em;
  padding: 0.85em 1em 0.7em;
  animation: aia-checkpoint-rewind-clock var(--d) cubic-bezier(0.55, 0, 0.25, 1) infinite;
}
.aia-checkpoint-rewind-head,
.aia-checkpoint-rewind-rail,
.aia-checkpoint-rewind-files {
  animation: aia-checkpoint-rewind-fade var(--d) linear infinite;
}
.aia-checkpoint-rewind-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.86em;
  font-weight: 600;
}
.aia-checkpoint-rewind-title { display: grid; }
.aia-checkpoint-rewind-title > * {
  grid-area: 1 / 1;
  display: inline-flex;
  align-items: center;
  gap: 0.45em;
  white-space: nowrap;
}
.aia-checkpoint-rewind-title svg {
  width: 1.05em;
  height: 1.05em;
  stroke-width: 2.4;
}
.aia-checkpoint-rewind-go { opacity: calc(1 - var(--q)); }
.aia-checkpoint-rewind-go svg {
  color: var(--c);
  animation: aia-checkpoint-rewind-spin 1.2s linear infinite;
}
.aia-checkpoint-rewind-done {
  opacity: var(--q);
  transform: translateY(calc((1 - var(--q)) * 0.4em));
}
.aia-checkpoint-rewind-done svg {
  color: color-mix(in srgb, #16a34a 78%, currentColor);
  stroke-width: 3;
}
.aia-checkpoint-rewind-count {
  color: color-mix(in srgb, currentColor 50%, transparent);
  font: 500 0.85em ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  --aia-checkpoint-rewind-n: calc(clamp(0, (var(--t) - 1.1) * 5, 1) + clamp(0, (var(--t) - 1.4) * 5, 1) + clamp(0, (var(--t) - 1.7) * 5, 1) - 0.4);
  counter-reset: n var(--aia-checkpoint-rewind-n);
}
.aia-checkpoint-rewind-count::before { content: counter(n) "/3 files"; }
.aia-checkpoint-rewind-rail {
  position: relative;
  height: 2.4em;
  margin: 0.8em 1.3em 0.2em;
}
.aia-checkpoint-rewind-line {
  position: absolute;
  left: 0;
  right: 0;
  top: 0.45em;
  height: 0.12em;
  background: repeating-linear-gradient(90deg, color-mix(in srgb, currentColor 26%, transparent) 0 0.35em, transparent 0.35em 0.6em);
}
.aia-checkpoint-rewind-line::before {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--c);
  transform: scaleX(calc(var(--pos) / 4));
  transform-origin: left;
}
.aia-checkpoint-rewind-cp {
  --i: 0;
  --on: clamp(0, (var(--pos) - var(--i) + 0.5) * 3, 1);
  --here: clamp(0, 1 - max(var(--pos) - var(--i), var(--i) - var(--pos)) * 2.5, 1);
  position: absolute;
  top: 0;
  left: calc(var(--i) * 25%);
  display: grid;
  justify-items: center;
  gap: 0.35em;
  width: 4.5em;
  margin-left: -2.25em;
}
.aia-checkpoint-rewind-cp:nth-child(3) { --i: 1; }
.aia-checkpoint-rewind-cp:nth-child(4) { --i: 2; }
.aia-checkpoint-rewind-cp:nth-child(5) { --i: 3; }
.aia-checkpoint-rewind-cp:nth-child(6) { --i: 4; }
.aia-checkpoint-rewind-cp i {
  box-sizing: border-box;
  width: 1.02em;
  height: 1.02em;
  border-radius: 50%;
  background: color-mix(in srgb, var(--c) calc(var(--on) * 100%), transparent);
  border: 0.13em solid color-mix(in srgb, var(--c) calc(var(--on) * 100%), color-mix(in srgb, currentColor 30%, transparent));
}
.aia-checkpoint-rewind-cp em {
  color: color-mix(in srgb, var(--c) calc(var(--here) * 85%), color-mix(in srgb, currentColor 50%, transparent));
  font-size: 0.66em;
  font-style: normal;
  font-weight: calc(500 + var(--here) * 200);
  opacity: calc(0.55 + var(--on) * 0.45);
  white-space: nowrap;
}
.aia-checkpoint-rewind-marker {
  position: absolute;
  top: calc(0.51em - 0.85em);
  left: calc(var(--pos) * 25%);
  width: 1.7em;
  height: 1.7em;
  margin-left: -0.85em;
  border-radius: 50%;
  box-shadow: 0 0 0 0.12em var(--c), 0 0 0 0.4em color-mix(in srgb, var(--c) 16%, transparent);
}
.aia-checkpoint-rewind-files {
  display: grid;
  gap: 0.1em;
  margin: 0.25em 0 0;
  padding: 0.5em 0 0;
  border-top: 1px solid color-mix(in srgb, currentColor 9%, transparent);
  list-style: none;
}
.aia-checkpoint-rewind-files li {
  --i: 0;
  --r: clamp(0, (var(--t) - 1.1 - var(--i) * 0.3) * 5, 1);
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 1.55em;
  font-size: 0.78em;
}
.aia-checkpoint-rewind-files li:nth-child(2) { --i: 1; }
.aia-checkpoint-rewind-files li:nth-child(3) { --i: 2; }
.aia-checkpoint-rewind-files code {
  font: 0.94em ui-monospace, "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
  opacity: calc(1 - var(--r) * 0.3);
}
.aia-checkpoint-rewind-files li:nth-child(3) code {
  text-decoration: line-through color-mix(in srgb, currentColor calc(var(--r) * 60%), transparent);
}
.aia-checkpoint-rewind-tag {
  display: grid;
  justify-items: end;
  font-size: 0.88em;
  font-weight: 600;
}
.aia-checkpoint-rewind-tag em {
  grid-area: 1 / 1;
  padding: 0.1em 0.5em;
  border-radius: 999em;
  font-style: normal;
}
.aia-checkpoint-rewind-tag em:first-child {
  background: color-mix(in srgb, #d97706 13%, transparent);
  color: color-mix(in srgb, #d97706 84%, currentColor);
  opacity: calc(1 - var(--r));
}
.aia-checkpoint-rewind-tag em:last-child {
  background: color-mix(in srgb, #16a34a 13%, transparent);
  color: color-mix(in srgb, #16a34a 78%, currentColor);
  opacity: var(--r);
  transform: scale(calc(0.8 + var(--r) * 0.2));
}
.aia-checkpoint-rewind-files li:nth-child(3) .aia-checkpoint-rewind-tag em:last-child {
  background: color-mix(in srgb, currentColor 8%, transparent);
  color: color-mix(in srgb, currentColor 60%, transparent);
}
@keyframes aia-checkpoint-rewind-clock {
  0%, 12% { --aia-checkpoint-rewind-t: 0; }
  21%, 24% { --aia-checkpoint-rewind-t: 0.5; }
  33%, 37% { --aia-checkpoint-rewind-t: 1; }
  58% { --aia-checkpoint-rewind-t: 2.2; }
  60%, 95.5% { --aia-checkpoint-rewind-t: 2.3; }
  96.5%, 100% { --aia-checkpoint-rewind-t: 0; }
}
@keyframes aia-checkpoint-rewind-fade {
  0%, 93% { opacity: 1; }
  95.5%, 97% { opacity: 0; }
  100% { opacity: 1; }
}
@keyframes aia-checkpoint-rewind-spin {
  to { transform: rotate(-360deg); }
}
@media (prefers-reduced-motion: reduce) {
  .aia-checkpoint-rewind,
  .aia-checkpoint-rewind-head,
  .aia-checkpoint-rewind-rail,
  .aia-checkpoint-rewind-files,
  .aia-checkpoint-rewind-go svg {
    animation: none;
    --aia-checkpoint-rewind-t: 2.3;
  }
}

@media (prefers-reduced-motion: reduce) {
  .aia-checkpoint-rewind, .aia-checkpoint-rewind *, .aia-checkpoint-rewind::before, .aia-checkpoint-rewind::after, .aia-checkpoint-rewind *::before, .aia-checkpoint-rewind *::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.

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