freeCodeCamp/curriculum/challenges/chinese/01-responsive-web-design/basic-css/use-a-media-query-to-change-a-variable.chinese.md

---
id: 5a9d72ad424fe3d0e10cad16
title: Use a media query to change a variable
challengeType: 0
videoUrl: 'https://scrimba.com/c/cWmL8UP'
forumTopicId: 301091
localeTitle: 使用媒体查询更改变量
---

## Description
<section id='description'>
CSS 变量可以简化媒体查询的方式。
例如，当屏幕小于或大于媒体查询所设置的值，通过改变变量的值，那么应用了变量的元素样式都会得到响应修改。
</section>

## Instructions
<section id='instructions'>
在<code>media query（媒体查询）</code>声明的<code>:root</code>选择器里，重定义<code>--penguin-size</code>的值为 200px，且重定义<code>--penguin-skin</code>的值为<code>black</code>，然后通过缩放页面来查看是否生效。
</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: '<code>:root</code>中的<code>--penguin-size</code>值应为<code>200px</code>。'
    testString: 'assert(code.match(/media\s*?\(\s*?max-width\s*?:\s*?350px\s*?\)\s*?{[\s\S]*:root\s*?{[\s\S]*--penguin-size\s*?:\s*?200px\s*?;[\s\S]*}[\s\S]*}/gi));'
  - text: '<code>:root</code>中的<code>--penguin-skin</code>值应为<code>black</code>。'
    testString: 'assert(code.match(/media\s*?\(\s*?max-width\s*?:\s*?350px\s*?\)\s*?{[\s\S]*:root\s*?{[\s\S]*--penguin-skin\s*?:\s*?black\s*?;[\s\S]*}[\s\S]*}/gi));'

```

</section>

## Challenge Seed
<section id='challengeSeed'>

<div id='html-seed'>

```html
<style>
  :root {
    --penguin-size: 300px;
    --penguin-skin: gray;
    --penguin-belly: white;
    --penguin-beak: orange;
  }
  
  @media (max-width: 350px) {
    :root {
      
      /* add code below */
      
      /* add code above */
      
    }
  }
  
  .penguin {
    position: relative;
    margin: auto;
    display: block;
    margin-top: 5%;
    width: var(--penguin-size, 300px);
    height: var(--penguin-size, 300px);
  }
  
  .right-cheek {
    top: 15%;
    left: 35%;
    background: var(--penguin-belly, white);
    width: 60%;
    height: 70%;
    border-radius: 70% 70% 60% 60%;
  }
  
  .left-cheek {
    top: 15%;
    left: 5%;
    background: var(--penguin-belly, white);
    width: 60%;
    height: 70%;
    border-radius: 70% 70% 60% 60%;
  }
  
  .belly {
    top: 60%;
    left: 2.5%;
    background: var(--penguin-belly, white);
    width: 95%;
    height: 100%;
    border-radius: 120% 120% 100% 100%;
  }
  
  .penguin-top {
    top: 10%;
    left: 25%;
    background: var(--penguin-skin, gray);
    width: 50%;
    height: 45%;
    border-radius: 70% 70% 60% 60%;
  }
  
  .penguin-bottom {
    top: 40%;
    left: 23.5%;
    background: var(--penguin-skin, gray);
    width: 53%;
    height: 45%;
    border-radius: 70% 70% 100% 100%;
  }
  
  .right-hand {
    top: 5%;
    left: 25%;
    background: var(--penguin-skin, black);
    width: 30%;
    height: 60%;
    border-radius: 30% 30% 120% 30%;
    transform: rotate(130deg);
    z-index: -1;
    animation-duration: 3s;
    animation-name: wave;
    animation-iteration-count: infinite;
    transform-origin:0% 0%;
    animation-timing-function: linear;
  }
  
  @keyframes wave {
      10% {
        transform: rotate(110deg);
      }
      20% {
        transform: rotate(130deg);
      }
      30% {
        transform: rotate(110deg);
      } 
      40% {
        transform: rotate(130deg);
      }  
    }
  
  .left-hand {
    top: 0%;
    left: 75%;
    background: var(--penguin-skin, gray);
    width: 30%;
    height: 60%;
    border-radius: 30% 30% 30% 120%;
    transform: rotate(-45deg);
    z-index: -1;
  }
  
  .right-feet {
    top: 85%;
    left: 60%;
    background: var(--penguin-beak, orange);
    width: 15%;
    height: 30%;
    border-radius: 50% 50% 50% 50%;
    transform: rotate(-80deg);
    z-index: -2222;
  }
  
  .left-feet {
    top: 85%;
    left: 25%;
    background: var(--penguin-beak, orange);
    width: 15%;
    height: 30%;
    border-radius: 50% 50% 50% 50%;
    transform: rotate(80deg);
    z-index: -2222;
  }
  
  .right-eye {
    top: 45%;
    left: 60%;
    background: black;
    width: 15%;
    height: 17%;
    border-radius: 50%;
  }
  
  .left-eye {
    top: 45%;
    left: 25%;
    background: black;
    width: 15%;
    height: 17%;
    border-radius: 50%;
  }
  
  .sparkle {
    top: 25%;
    left:-23%;
    background: white;
    width: 150%;
    height: 100%;
    border-radius: 50%;
  }
  
  .blush-right {
    top: 65%;
    left: 15%;
    background: pink;
    width: 15%;
    height: 10%;
    border-radius: 50%;
  }
  
  .blush-left {
    top: 65%;
    left: 70%;
    background: pink;
    width: 15%;
    height: 10%;
    border-radius: 50%;
  }
  
  .beak-top {
    top: 60%;
    left: 40%;
    background: var(--penguin-beak, orange);
    width: 20%;
    height: 10%;
    border-radius: 50%;
  }
  
  .beak-bottom {
    top: 65%;
    left: 42%;
    background: var(--penguin-beak, orange);
    width: 16%;
    height: 10%;
    border-radius: 50%;
  }
  
  body {
    background:#c6faf1;
  }
  
  .penguin * {
    position: absolute;
  }
</style>
<div class="penguin">
  <div class="penguin-bottom">
    <div class="right-hand"></div>
    <div class="left-hand"></div>
    <div class="right-feet"></div>
    <div class="left-feet"></div>
  </div>
  <div class="penguin-top">
    <div class="right-cheek"></div>
    <div class="left-cheek"></div>
    <div class="belly"></div>
    <div class="right-eye">
      <div class="sparkle"></div>
    </div>
    <div class="left-eye">
      <div class="sparkle"></div>
    </div>
    <div class="blush-right"></div>
    <div class="blush-left"></div>
    <div class="beak-top"></div>
    <div class="beak-bottom"></div>
  </div>
</div>
```

</div>



</section>

## Solution
<section id='solution'>


```js
// solution required
```

</section>