freeCodeCamp/curriculum/challenges/english/01-responsive-web-design/applied-visual-design/animate-multiple-elements-at-variable-rates.md

---
id: 587d78a8367417b2b2512ae6
title: Animate Multiple Elements at Variable Rates
challengeType: 0
videoUrl: 'https://scrimba.com/c/cnpWZc9'
forumTopicId: 301042
dashedName: animate-multiple-elements-at-variable-rates
---

# --description--

In the previous challenge, you changed the animation rates for two similarly animated elements by altering their `@keyframes` rules. You can achieve the same goal by manipulating the `animation-duration` of multiple elements.

In the animation running in the code editor, there are three stars in the sky that twinkle at the same rate on a continuous loop. To make them twinkle at different rates, you can set the `animation-duration` property to different values for each element.

# --instructions--

Set the `animation-duration` of the elements with the classes `star-1`, `star-2`, and `star-3` to 1s, 0.9s, and 1.1s, respectively.

# --hints--

The `animation-duration` property for the star with class `star-1` should remain at 1s.

```js
assert($('.star-1').css('animation-duration') == '1s');
```

The `animation-duration` property for the star with class `star-2` should be 0.9s.

```js
assert($('.star-2').css('animation-duration') == '0.9s');
```

The `animation-duration` property for the star with class `star-3` should be 1.1s.

```js
assert($('.star-3').css('animation-duration') == '1.1s');
```

# --seed--

## --seed-contents--

```html
<style>
  .stars {
    background-color: white;
    height: 30px;
    width: 30px;
    border-radius: 50%;
    animation-iteration-count: infinite;
  }

  .star-1 {
    margin-top: 15%;
    margin-left: 60%;
    animation-duration: 1s;
    animation-name: twinkle;
  }

  .star-2 {
    margin-top: 25%;
    margin-left: 25%;
    animation-duration: 1s;
    animation-name: twinkle;
  }

  .star-3 {
    margin-top: 10%;
    margin-left: 50%;
    animation-duration: 1s;
    animation-name: twinkle;
  }

  @keyframes twinkle {
    20% {
      transform: scale(0.5);
      opacity: 0.5;
    }
  }

  #back {
    position: fixed;
    padding: 0;
    margin: 0;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(black, #000099, #66c2ff, #ffcccc, #ffeee6);
  }
</style>

<div id="back"></div>
<div class="star-1 stars"></div>
<div class="star-2 stars"></div>
<div class="star-3 stars"></div>
```

# --solutions--

```html
<style>
  .stars {
    background-color: white;
    height: 30px;
    width: 30px;
    border-radius: 50%;
    animation-iteration-count: infinite;
  }

  .star-1 {
    margin-top: 15%;
    margin-left: 60%;
    animation-duration: 1s;
    animation-name: twinkle;
  }

  .star-2 {
    margin-top: 25%;
    margin-left: 25%;
    animation-duration: 0.9s;
    animation-name: twinkle;
  }

  .star-3 {
    margin-top: 10%;
    margin-left: 50%;
    animation-duration: 1.1s;
    animation-name: twinkle;
  }

  @keyframes twinkle {
    20% {
      transform: scale(0.5);
      opacity: 0.5;
    }
  }

  #back {
    position: fixed;
    padding: 0;
    margin: 0;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(black, #000099, #66c2ff, #ffcccc, #ffeee6);
  }
</style>
<div id="back"></div>
<div class="star-1 stars"></div>
<div class="star-2 stars"></div>
<div class="star-3 stars"></div>
```