2018-10-10 22:03:03 +00:00
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---
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id: 587d781e367417b2b2512acc
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challengeType: 0
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2020-02-11 07:46:34 +00:00
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videoUrl: 'https://scrimba.com/c/c2MDNUR'
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forumTopicId: 301061
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2020-10-01 15:54:21 +00:00
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title: 固定定位的参照物是浏览器的窗口
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2018-10-10 22:03:03 +00:00
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---
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## Description
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2020-02-11 07:46:34 +00:00
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<section id='description'>
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接下来要介绍的是 <code>fixed</code> 定位，它是一种特殊的绝对（absolute）定位，区别是其包含块是浏览器窗口。和绝对定位类似，<code>fixed</code> 定位使用 top、bottom、left 和 right 属性来调整元素的位置，并且会将元素从当前的文档流里面移除，其它元素会忽略它的存在。
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<code>fixed</code> 定位和 <code>absolute</code> 定位的最明显的区别是 <code>fixed</code> 定位元素不会随着屏幕滚动而移动。
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</section>
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2018-10-10 22:03:03 +00:00
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## Instructions
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2020-02-11 07:46:34 +00:00
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<section id='instructions'>
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2020-03-03 13:41:15 +00:00
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代码里的导航栏已经添加了值为 <code>navbar</code> 的 id。把它的 <code>position</code> 设置成<code>fixed</code>，设定其 <code>top</code >和 <code>left</code> 为 0 像素。添加代码之后，滑动预览窗口，观察导航栏的位置。
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2020-02-11 07:46:34 +00:00
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</section>
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2018-10-10 22:03:03 +00:00
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## Tests
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<section id='tests'>
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```yml
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tests:
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2020-02-11 07:46:34 +00:00
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- text: '<code>>#navbar</code> 元素应当有一个值为 <code>fixed</code> 的 <code>position</code> CSS 属性'
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2020-02-17 16:40:55 +00:00
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testString: assert($('#navbar').css('position') == 'fixed');
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2020-02-11 07:46:34 +00:00
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- text: '你的 <code>#navbar</code> 元素应当有值为 <code>0px</code> 的 <code>top</code> CSS 属性。'
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2020-02-17 16:40:55 +00:00
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testString: assert($('#navbar').css('top') == '0px');
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2020-02-11 07:46:34 +00:00
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- text: '你的 <code>#navbar</code> 元素应当有值为 <code>0px</code> 的 <code>left</code> CSS 属性。'
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2020-02-17 16:40:55 +00:00
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testString: assert($('#navbar').css('left') == '0px');
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2018-10-10 22:03:03 +00:00
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='html-seed'>
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```html
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<style>
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#navbar {
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2020-02-11 07:46:34 +00:00
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2018-10-10 22:03:03 +00:00
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width: 100%;
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background-color: #767676;
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}
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nav ul {
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margin: 0px;
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padding: 5px 0px 5px 30px;
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}
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nav li {
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display: inline;
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margin-right: 20px;
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}
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a {
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text-decoration: none;
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}
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</style>
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<body>
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<header>
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2020-02-11 07:46:34 +00:00
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<h1>欢迎!</h1>
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2018-10-10 22:03:03 +00:00
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<nav id="navbar">
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<ul>
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2020-02-11 07:46:34 +00:00
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<li><a href="">网站首页</a></li>
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<li><a href="">联系我们</a></li>
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2018-10-10 22:03:03 +00:00
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</ul>
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</nav>
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</header>
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2020-02-11 07:46:34 +00:00
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<p>当导航条固定在浏览器窗口上时，我会上移。</p>
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2018-10-10 22:03:03 +00:00
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</body>
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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2020-02-11 07:46:34 +00:00
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```html
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2018-10-10 22:03:03 +00:00
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// solution required
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```
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2020-02-11 07:46:34 +00:00
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2018-10-10 22:03:03 +00:00
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</section>
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2020-02-11 07:46:34 +00:00
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