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如何实现CSS居中？?CSS居中常用方法_html/css_WEB-ITnose

WBOY
WBOY原创
2016-06-24 11:57:021344浏览

来源：http://www.ido321.com/824.html

一、水平居中

      1、内联元素居中：相对父级块级元素居中对齐

   1: .center-children {
   2:   text-align: center;
   3: }

 

      2、块级元素居中：设置margin-left和margin-right为auto让它居中（同时还要设置width，否则它就会承满整个容器，无法看出居中效果） 

   1: .center-me {
   2:   margin: 0 auto;
   3: }

 

如果有很多块级元素需要水平居中成一行，最好使用一个不同的display类型。这是一个使用inline-block和flex的例子。

演示地址：http://jsfiddle.net/Web_Code/5fvrwwk1/embedded/result/

   1: <main class="inline-block-center"></main>
   2:   <div>    <pre style="代码" class="precsshei">   3:     I'm an element that is block-like with my siblings and we're centered in a row.
   4:   
   5:   <div>    <pre style="代码" class="precsshei">   6:     I'm an element that is block-like with my siblings and we're centered in a row. I have more content in me than my siblings do.
   7:   
   8:   <div>    <pre style="代码" class="precsshei">   9:     I'm an element that is block-like with my siblings and we're centered in a row.
  10:   
  11: 
  12: <main class="flex-center"></main>
  13:   <div>    <pre style="代码" class="precsshei">  14:     I'm an element that is block-like with my siblings and we're centered in a row.
  15:   
  16:   <div>    <pre style="代码" class="precsshei">  17:     I'm an element that is block-like with my siblings and we're centered in a row. I have more content in me than my siblings do.
  18:   
  19:   <div>    <pre style="代码" class="precsshei">  20:     I'm an element that is block-like with my siblings and we're centered in a row.
  21:   
  22:

css:

   1: body {
   2:   background: #f06d06;
   3:   font-size: 80%;
   4: }
   5: main {
   6:   background: white;
   7:   margin: 20px 0;
   8:   padding: 10px;
   9: }
  10: main div {
  11:   background: black;
  12:   color: white;
  13:   padding: 15px;
  14:   max-width: 125px;
  15:   margin: 5px;
  16: }
  17: .inline-block-center {
  18:   text-align: center;
  19: }
  20: .inline-block-center div {
  21:   display: inline-block;
  22:   text-align: left;
  23: }
  24: .flex-center {
  25:   display: flex;
  26:   justify-content: center;
  27: }

二、垂直居中

       1、内联元素：设置相等的上下padding，或者利用line-height

   1: .link {
   2:   padding-top: 30px;
   3:   padding-bottom: 30px;
   4: }

文本不会换行的情况下，可以使用line-height，让其与height相等去对齐文本。

   1: .center-text-trick {
   2:   height: 100px;
   3:   line-height: 100px;
   4:   white-space: nowrap;
   5: }

 

多行的文本也可以利用上下等padding的方式也可以让多行居中，但是如果这方法没用，你可以让这些文字的容器按table cell模式显示，然后设置文字的vertical-align属性对齐，

演示地址： http://jsfiddle.net/Web_Code/5fvrwwk1/1/embedded/result/

html: 

   1: 
   2:   <tr>    <pre style="代码" class="precsshei">   3:     <td>    <pre style="代码" class="precsshei">   4:       I'm vertically centered multiple lines of text in a real table cell.
   5:     
   6:   
   7: 
   8: <div class="center-table">    <pre style="代码" class="precsshei">   9:   <p>I'm vertically centered multiple lines of text in a CSS-created table layout.</p>
  10:

css

   1: body {
   2:   background: #f06d06;
   3:   font-size: 80%;
   4: }
   5: table {
   6:   background: white;
   7:   width: 240px;
   8:   border-collapse: separate;
   9:   margin: 20px;
  10:   height: 250px;
  11: }
  12: table td {
  13:   background: black;
  14:   color: white;
  15:   padding: 20px;
  16:   border: 10px solid white;
  17:   /* default is vertical-align: middle; */
  18: }
  19: .center-table {
  20:   display: table;
  21:   height: 250px;
  22:   background: white;
  23:   width: 240px;
  24:   margin: 20px;
  25: }
  26: .center-table p {
  27:   display: table-cell;
  28:   margin: 0;
  29:   background: black;
  30:   color: white;
  31:   padding: 20px;
  32:   border: 10px solid white;
  33:   vertical-align: middle;
  34: }

 

     2、块级元素

若元素有固定高度，可以这样垂直居中

   1: .parent {
   2:   position: relative;
   3: }
   4: .child {
   5:   position: absolute;
   6:   top: 50%;
   7:   height: 100px;
   8:   margin-top: -50px; /* 如果没有使用: border-box; 的盒子模型则需要设置这个 */
   9: }

如果不知道元素高度，则这样

   1: .parent {
   2:   position: relative;
   3: }
   4: .child {
   5:   position: absolute;
   6:   top: 50%;
   7:   transform: translateY(-50%);
   8: }

也可以使用flexbox

   1: <main>  </main>
   2:   <div>    <pre style="代码" class="precsshei">   3:      I'm a block-level element with an unknown height, centered vertically within my parent.
   4:   
   5: 

   1: body {
   2:   background: #f06d06;
   3:   font-size: 80%;
   4: }
   5: main {
   6:   background: white;
   7:   height: 300px;
   8:   width: 200px;
   9:   padding: 20px;
  10:   margin: 20px;
  11:   display: flex;
  12:   flex-direction: column;
  13:   justify-content: center;
  14:   resize: vertical;
  15:   overflow: auto;
  16: }
  17: main div {
  18:   background: black;
  19:   color: white;
  20:   padding: 20px;
  21:   resize: vertical;
  22:   overflow: auto;
  23: }

 

三、同时水平和垂直居中

      1、元素有固定高度和宽度：先绝对居中，然后上移和左移50%的宽度即可

   1: //这种方案有极好的跨浏览器支持。
   2: .parent {
   3:   position: relative;
   4: }
   5: .child {
   6:   width: 300px;
   7:   height: 100px;
   8:   padding: 20px;
   9:   position: absolute;
  10:   top: 50%;
  11:   left: 50%;
  12:   margin: -70px 0 0 -170px;
  13: }

 

     2、元素的高度和宽度未知或可变的：使用transofrm属性在两个方向都平移负50%

   1: .parent {
   2:   position: relative;
   3: }
   4: .child {
   5:   position: absolute;
   6:   top: 50%;
   7:   left: 50%;
   8:   transform: translate(-50%, -50%);
   9: }
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