css-animations

Original：🇺🇸 English

Translated

CSS animation adapter patterns for HyperFrames. Use when authoring CSS keyframes, animation-delay based timing, animation-fill-mode, animation-play-state, or CSS-only motion that HyperFrames must seek deterministically during preview and rendering.

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Sourceheygen-com/hyperframes

Added on2026-04-30

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CSS Animations for HyperFrames

HyperFrames can seek CSS keyframe animations through its

css

runtime adapter. Use this for simple repeated motifs, background motion, shimmer, glow, masks, and non-sequenced decoration.

For scene choreography, GSAP is usually clearer. CSS animations work best when the motion belongs to one element and has a fixed duration.

Contract

Put the animated element in the DOM before runtime initialization finishes.
Give timed elements a
```
data-start
```
value so local animation time matches the clip.
Use finite
```
animation-duration
```
and
```
animation-iteration-count
```
because the negative-delay fallback cannot represent unbounded duration in environments without WAAPI-backed CSS animations.
Prefer
```
animation-fill-mode: both
```
so seeked states hold before and after active motion.
Avoid wall-clock JavaScript, hover-triggered state, and class toggles that depend on user events.

The adapter discovers elements with computed

animation-name

, seeks their browser

Animation

handles when available, and falls back to pausing with negative

animation-delay

.

Basic Pattern

html

<div
  id="pulse-ring"
  class="clip pulse-ring"
  data-start="0"
  data-duration="4"
  data-track-index="2"
></div>

<style>
  .pulse-ring {
    width: 280px;
    height: 280px;
    border: 4px solid rgba(255, 255, 255, 0.7);
    border-radius: 50%;
    animation-name: pulse-ring;
    animation-duration: 1200ms;
    animation-timing-function: cubic-bezier(0.2, 0, 0, 1);
    animation-iteration-count: 3;
    animation-fill-mode: both;
  }

  @keyframes pulse-ring {
    from {
      opacity: 0;
      transform: scale(0.82);
    }
    35% {
      opacity: 1;
    }
    to {
      opacity: 0;
      transform: scale(1.18);
    }
  }
</style>

Stagger Pattern

Use CSS custom properties to avoid duplicating keyframes:

html

<div class="clip dots" data-start="1" data-duration="3" data-track-index="3">
  <span style="--i: 0"></span>
  <span style="--i: 1"></span>
  <span style="--i: 2"></span>
</div>

<style>
  .dots span {
    display: inline-block;
    width: 18px;
    height: 18px;
    margin-right: 10px;
    border-radius: 50%;
    background: currentColor;
    animation: dot-pop 900ms ease-out both;
    animation-delay: calc(var(--i) * 120ms);
  }

  @keyframes dot-pop {
    from {
      opacity: 0;
      transform: translateY(18px) scale(0.75);
    }
    to {
      opacity: 1;
      transform: translateY(0) scale(1);
    }
  }
</style>

Good Uses

Decorative loops with a known repeat count.
Mask, glow, shimmer, grain, and subtle parallax layers.
Simple one-element entrances where a full JS timeline would be excessive.

Avoid

Infinite CSS animations unless you have verified the browser exposes seekable WAAPI-backed CSS animation handles. Prefer a finite iteration count covering the visible duration.
Animating layout properties like
```
top
```
,
```
left
```
,
```
width
```
, or
```
height
```
when transforms work.
Relying on hover, focus, scroll, or media queries to trigger render-critical motion.
Changing animation classes after startup unless another deterministic timeline controls that change.

Validation

After editing CSS animation compositions:

bash

npx hyperframes lint
npx hyperframes validate

Credits And References

HyperFrames adapter source:

packages/core/src/runtime/adapters/css.ts

.

MDN CSS animation documentation: https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties/animation
MDN
```
animation-fill-mode
```
: https://developer.mozilla.org/en-US/docs/Web/CSS/animation-fill-mode