html - 如何水平对齐 ul 到 div 的中心？

Question

我正在尝试将 <ul> 居中在 <div> 里面.我尝试了以下

text-align: center;

和

left: 50%;

这是行不通的。

CSS:

.container { 
    clear: both; 
    width: 800px; 
    height: 70px; 
    margin-bottom: 10px;
    text-align: center;
}

.container ul { 
    padding: 0 0 0 20px; 
    margin: 0; 
    list-style: none;
}

.container ul li { 
    margin: 0; 
    padding: 0; 
}

我想要 ul在容器内居中。

Answer 1

以下是在 CSS 中水平居中的解决方案列表。该代码段包括所有这些内容。

html {
  font: 1.25em/1.5 Georgia, Times, serif;
}

pre {
  color: #fff;
  background-color: #333;
  padding: 10px;
}

blockquote {
  max-width: 400px;
  background-color: #e0f0d1;
}

blockquote > p {
  font-style: italic;
}

blockquote > p:first-of-type::before {
  content: open-quote;
}

blockquote > p:last-of-type::after {
  content: close-quote;
}

blockquote > footer::before {
  content: "\2014";
}

.container,
blockquote {
  position: relative;
  padding: 20px;
}

.container {
  background-color: tomato;
}

.container::after,
blockquote::after {
  position: absolute;
  right: 0;
  bottom: 0;
  padding: 2px 10px;
  border: 1px dotted #000;
  background-color: #fff;
}

.container::after {
  content: ".container-" attr(data-num);
  z-index: 1;
}

blockquote::after {
  content: ".quote-" attr(data-num);
  z-index: 2;
}

.container-4 {
  margin-bottom: 200px;
}

/**
 * Solution 1
 */
.quote-1 {
  max-width: 400px;
  margin-right: auto;
  margin-left: auto;
}

/**
 * Solution 2
 */
.container-2 {
  text-align: center;
}

.quote-2 {
  display: inline-block;
  text-align: left;
}

/**
 * Solution 3
 */
.quote-3 {
  display: table;
  margin-right: auto;
  margin-left: auto;
}

/**
 * Solution 4
 */
.container-4 {
  position: relative;
}

.quote-4 {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
}

/**
 * Solution 5
 */
.container-5 {
  display: flex;
  justify-content: center;
}

<main>
  <h1>CSS: Horizontal Centering</h1>

  <h2>Uncentered Example</h2>
  <p>This is the scenario: We have a container with an element inside of it that we want to center. I just added a little padding and background colors so both elements are distinquishable.</p>

  <div class="container  container-0" data-num="0">
    <blockquote class="quote-0" data-num="0">
      <p>My friend Data. You see things with the wonder of a child. And that makes you more human than any of us.</p>
      <footer>Tasha Yar about Data</footer>
    </blockquote>
  </div>

  <h2>Solution 1: Using <code>max-width</code> & <code>margin</code> (IE7)</h2>

  <p>This method is widely used. The upside here is that only the element which one wants to center needs rules.</p>

<pre><code>.quote-1 {
  max-width: 400px;
  margin-right: auto;
  margin-left: auto;
}</code></pre>

  <div class="container  container-1" data-num="1">
    <blockquote class="quote  quote-1" data-num="1">
      <p>My friend Data. You see things with the wonder of a child. And that makes you more human than any of us.</p>
      <footer>Tasha Yar about Data</footer>
    </blockquote>
  </div>

  <h2>Solution 2: Using <code>display: inline-block</code> and <code>text-align</code> (IE8)</h2>

  <p>This method utilizes that <code>inline-block</code> elements are treated as text and as such they are affected by the <code>text-align</code> property. This does not rely on a fixed width which is an upside. This is helpful for when you don’t know the number of elements in a container for example.</p>

<pre><code>.container-2 {
  text-align: center;
}

.quote-2 {
  display: inline-block;
  text-align: left;
}</code></pre>

  <div class="container  container-2" data-num="2">
    <blockquote class="quote  quote-2" data-num="2">
      <p>My friend Data. You see things with the wonder of a child. And that makes you more human than any of us.</p>
      <footer>Tasha Yar about Data</footer>
    </blockquote>
  </div>

  <h2>Solution 3: Using <code>display: table</code> and <code>margin</code> (IE8)</h2>

  <p>Very similar to the second solution but only requires to apply rules on the element that is to be centered.</p>

<pre><code>.quote-3 {
  display: table;
  margin-right: auto;
  margin-left: auto;
}</code></pre>

  <div class="container  container-3" data-num="3">
    <blockquote class="quote  quote-3" data-num="3">
      <p>My friend Data. You see things with the wonder of a child. And that makes you more human than any of us.</p>
      <footer>Tasha Yar about Data</footer>
    </blockquote>
  </div>

  <h2>Solution 4: Using <code>translate()</code> and <code>position</code> (IE9)</h2>

  <p>Don’t use as a general approach for horizontal centering elements. The downside here is that the centered element will be removed from the document flow. Notice the container shrinking to zero height with only the padding keeping it visible. This is what <i>removing an element from the document flow</i> means.</p>

  <p>There are however applications for this technique. For example, it works for <b>vertically</b> centering by using <code>top</code> or <code>bottom</code> together with <code>translateY()</code>.</p>

<pre><code>.container-4 {
    position: relative;
}

.quote-4 {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
}</code></pre>

  <div class="container  container-4" data-num="4">
    <blockquote class="quote  quote-4" data-num="4">
      <p>My friend Data. You see things with the wonder of a child. And that makes you more human than any of us.</p>
      <footer>Tasha Yar about Data</footer>
    </blockquote>
  </div>

  <h2>Solution 5: Using Flexible Box Layout Module (IE10+ with vendor prefix)</h2>

  <p></p>

<pre><code>.container-5 {
  display: flex;
  justify-content: center;
}</code></pre>

  <div class="container  container-5" data-num="5">
    <blockquote class="quote  quote-5" data-num="5">
      <p>My friend Data. You see things with the wonder of a child. And that makes you more human than any of us.</p>
      <footer>Tasha Yar about Data</footer>
    </blockquote>
  </div>
</main>

---

显示:flex

.container {
  display: flex;
  justify-content: center;
}

注意事项:

• 这不是黑客 👍👍👍
• Browser support: flexbox

---

最大宽度 & 边距

您可以通过指定固定宽度并将 margin-right 和 margin-left 设置为 auto 来水平居中 block 级元素。

.container ul {
  /* for IE below version 7 use `width` instead of `max-width` */
  max-width: 800px;
  margin-right: auto;
  margin-left: auto;
}

注意事项:

• 不需要容器 👍
• 需要已知居中元素的(最大)宽度 👎

---

IE9+: transform: translatex(-50%) & left: 50%

这类似于使用绝对定位和负边距的古怪居中方法。

.container {
  position: relative;
}

.container ul {
  position: absolute;
  left: 50%;
  transform: translatex(-50%);
}

注意事项:

• 居中元素将从文档流中移除。所有元素将完全忽略居中元素。 👎👎👎
• 此技术通过使用 top 而不是 left 和 translateY() 而不是 允许垂直居中>翻译X()。两者甚至可以结合。 👍
• Browser support: transform2d

---

IE8+: display: table & margin

就像第一个解决方案一样，您对左右边距使用自动值，但不指定宽度。如果您不需要支持 IE7 及更低版本，这更适合，尽管使用 table 属性值来显示 感觉有点老套。

.container ul {
  display: table;
  margin-right: auto;
  margin-left: auto;
}

---

IE8+: display: inline-block & text-align

也可以像处理常规文本一样使元素居中。缺点:您需要同时为容器和元素本身赋值。

.container {
  text-align: center;
}

.container ul {
  display: inline-block;

  /* One most likely needs to realign flow content */
  text-align: initial;
}

注意事项:

• 不需要指定(最大)宽度 👍
• 将流内容对齐到中心(可能是不需要的副作用)👎
• 适用于动态数量的菜单项(即在您不知道单个元素将占用的宽度的情况下)👍