<li> 元素中的文本居中对齐

Question

body {
 margin: 0;
}

.header {
    width: 80%;
    height: 20%;
    margin-left: 10%; 
    position: fixed;
    top: 0; 
    box-sizing: border-box;
    border-style: solid;
    border-width: 1px;
    background-color: green;
}

.image {
    width: 20%;
    height: 100%;
    float: left;
    box-sizing: border-box;
    border-style: solid;
    border-width: 1px;
}

.navigation {
    width: 79%;
    height: 100%;
    float: right;
    text-align: right;
    box-sizing: border-box;
    border-style: solid;
    border-width: 1px;
}

ul {
    height: 100%;
    font-size: 0;
    box-sizing: border-box;
    border-style: solid;
    border-width: 1px;
    background-color: yellow;
}

li {
    height: 100%;
    font-size: initial;
    display: inline-block;
    box-sizing: border-box;
 border-style: solid;
 border-width: 1px;
    background-color: blue;
}

<div class="header"> 

      <div class="image">
      Image
      </div>
  
      <nav class="navigation"> 
        <ul>
          <li> 1.0 Main Menu </li>
          <li> 2.0 Main Menu </li>
          <li> 3.0 Main Menu </li>
        </ul>
      </nav>
      
</div>

使用上面的代码，我创建了一个 <header>，其中包含一个 <image> 和一个 <navigation>。到目前为止，这一切都很好。

现在我希望 <li> 元素中的 text 出现在 center 中。因此，我尝试在 li CSS 中使用属性 text-align: center; 但它没有用。

我必须在我的代码中更改什么才能在 <li> 元素 centered 中获得 text？

你也可以在这里找到我的代码：https://jsfiddle.net/5jv8m5xf/39/

Answer 1

text-align:center 确实使文本居中——但是您必须为 li 元素设置一个特定的宽度；否则它们中的每一个都只是折叠到文本本身的宽度，所以居中是不可见的。

li {
  width: 100px; 
  text-align:center;
}
/* Everything below is the same as your original code */
body {
 margin: 0;
}

.header {
    width: 80%;
    height: 20%;
    margin-left: 10%; 
    position: fixed;
    top: 0; 
    box-sizing: border-box;
    border-style: solid;
    border-width: 1px;
    background-color: green;
}

.image {
    width: 20%;
    height: 100%;
    float: left;
    box-sizing: border-box;
    border-style: solid;
    border-width: 1px;
}

.navigation {
    width: 79%;
    height: 100%;
    float: right;
    text-align: right;
    box-sizing: border-box;
    border-style: solid;
    border-width: 1px;
}

ul {
    height: 100%;
    font-size: 0;
    box-sizing: border-box;
    border-style: solid;
    border-width: 1px;
    background-color: yellow;
}

li {
    height: 100%;
    font-size: initial;
    display: inline-block;
    box-sizing: border-box;
    border-style: solid;
    border-width: 1px;
    background-color: blue; 
}

<div class="header"> 

      <div class="image">
      Image
      </div>
  
      <nav class="navigation"> 
        <ul>
          <li> Longer text</li>
          <li> Short </li>
          <li> X </li>
        </ul>
      </nav>
      
</div>

如果你也想要垂直居中，有很多技巧——最快和最脏的方法是向 li 元素添加一些 padding-top，或者设置一个 line-height 匹配整个元素的高度。

但是针对这个特定设计的更简洁的解决方案可能是切换到 flexbox；代码有点简单，它解决了 li 中的文本换行时出现的布局问题：

.header {
  background-color: yellow;
  display: flex;
  justify-content: space-between; /* Puts the image at far left, nav at far right */
}

.image {
  width: 100px;
  background-color: green
}

ul {
  display: flex; /* Puts the `li` in a row */
  list-style: none; margin: 0; padding: 0;
  background-color: blue;
  height: 100px;
}

li {
  border: 1px solid;
  width: 100px; /* Alternatively, you could set a specific width on the ul, and use flex-grow:1 here to make all the li elements the same width */
  display: flex; /* allows align-items to work below */
  justify-content: center; /* Horizontally centers single-line elements */
  text-align:center; /* Horizontally centers text within line-wrapped elements */
  align-items: center; /* vertical */
}

<div class="header">
  <div class="image">
    Image
  </div>
  <nav class="navigation">
    <ul>
      <li>Very long text with line wrapping</li>
      <li>Short</li>
      <li>X</li>
    </ul>
  </nav>
</div>

Answer 2

将宽度设置为 li 以使 text-align: center 相关。

使用 psuedo 元素垂直对齐元素的一种方法 - 添加 vertical-align: middle 到您的 li 和这个 psuedo after 元素到你的 css:

li:after {
  content: '';
  height: 100%;
  display: inline-block;
  vertical-align: middle;
}

参见下面的演示：

body {
  margin: 0;
}

.header {
  width: 80%;
  height: 20%;
  margin-left: 10%;
  position: fixed;
  top: 0;
  box-sizing: border-box;
  border-style: solid;
  border-width: 1px;
  background-color: green;
}

.image {
  width: 20%;
  height: 100%;
  float: left;
  box-sizing: border-box;
  border-style: solid;
  border-width: 1px;
}

.navigation {
  width: 79%;
  height: 100%;
  float: right;
  text-align: right;
  box-sizing: border-box;
  border-style: solid;
  border-width: 1px;
}

ul {
  height: 100%;
  font-size: 0;
  box-sizing: border-box;
  border-style: solid;
  border-width: 1px;
  background-color: yellow;
}

li {
  height: 100%;
  font-size: initial;
  display: inline-block;
  box-sizing: border-box;
  border-style: solid;
  border-width: 1px;
  background-color: blue;
  text-align: center;
  vertical-align: middle;
}

li:after {
  content: '';
  height: 100%;
  display: inline-block;
  vertical-align: middle;
}

<div class="header">
  <div class="image">
    Image
  </div>
  <nav class="navigation">
    <ul>
      <li> 1.0 Main Menu </li>
      <li> 2.0 Main Menu </li>
      <li> 3.0 Main Menu </li>
    </ul>
  </nav>
</div>

如果 flexbox 是您可以使用 display: inline-flex 的选项，事情可以像为 [=46= 添加 justify-content: center 一样简单]水平和align-items: center用于垂直对齐。

参见下面的演示：

body {
  margin: 0;
}

.header {
  width: 80%;
  height: 20%;
  margin-left: 10%;
  position: fixed;
  top: 0;
  box-sizing: border-box;
  border-style: solid;
  border-width: 1px;
  background-color: green;
}

.image {
  width: 20%;
  height: 100%;
  float: left;
  box-sizing: border-box;
  border-style: solid;
  border-width: 1px;
}

.navigation {
  width: 79%;
  height: 100%;
  float: right;
  text-align: right;
  box-sizing: border-box;
  border-style: solid;
  border-width: 1px;
}

ul {
  height: 100%;
  font-size: 0;
  box-sizing: border-box;
  border-style: solid;
  border-width: 1px;
  background-color: yellow;
}

li {
  height: 100%;
  font-size: initial;
  display: inline-block;
  box-sizing: border-box;
  border-style: solid;
  border-width: 1px;
  background-color: blue;
  /*ADDED THESE*/
  display: inline-flex;
  justify-content: center;
  align-items: center;
}

<div class="header">
  <div class="image">
    Image
  </div>
  <nav class="navigation">
    <ul>
      <li> 1.0 Main Menu </li>
      <li> 2.0 Main Menu </li>
      <li> 3.0 Main Menu </li>
    </ul>
  </nav>
</div>

<li> 元素中的文本居中对齐

text-align center in <li> element

html

css

vertical-alignment

centering