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CSS中的垂直和水平居中完全指南

2015-07-10 09:09作者:fang

CSS Code

.link {

padding-top: 30px;

padding-bottom: 30px;

}

居中一直是CSS中被抱怨的典型。为什么实现起来这么辛苦?所以有人被嘲笑。我觉得问题不是没有办法做到,只是视情况而定,有很多不同方式,但是很难弄清楚应该用何种方式。因此我写了这篇文章,希望能把他变得容易点。

 水平居中

  内联元素(inline or inline-*)居中?

  你可以让他相对父级块级元素居中对齐

CSS Code

.center-children {

text-align: center;

}

  块级元素(block level)居中?

  你可以通过设置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),如。

CSS Code

.center-me {

margin: 0 <span style="width: auto; height: auto; float: none;" id="8_nwp"><a style="text-decoration: none;" mpid="8" target="_blank" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=0&is_app=0&jk=f3e358418dc3f42b&k=auto&k0=auto&kdi0=0&luki=3&n=10&p=baidu&q=06011078_cpr&rb=0&rs=1&seller_id=1&sid=2bf4c38d4158e3f3&ssp2=1&stid=0&t=tpclicked3_hc&tu=u1922429&u=http%3A%2F%2Fwww%2Eadmin10000%2Ecom%2Fdocument%2F5106%2Ehtml&urlid=0" id="8_nwl"><span style="color:#0000ff;font-size:14px;width:auto;height:auto;float:none;">auto</span></a></span>;

}

  如果有很多块级元素呢?

  如果你有很匀块级元素需要水平居中成一行,你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。

CSS Code

<main class="inline-block-center">

<div>

I'm an element that is block-like with my siblings and we're centered in a row.

</div>

<div>

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.

</div>

<div>

I'm an element that is <span style="width: auto; height: auto; float: none;" id="6_nwp"><a style="text-decoration: none;" mpid="6" target="_blank" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=0&is_app=0&jk=f3e358418dc3f42b&k=block&k0=block&kdi0=0&luki=2&n=10&p=baidu&q=06011078_cpr&rb=0&rs=1&seller_id=1&sid=2bf4c38d4158e3f3&ssp2=1&stid=0&t=tpclicked3_hc&tu=u1922429&u=http%3A%2F%2Fwww%2Eadmin10000%2Ecom%2Fdocument%2F5106%2Ehtml&urlid=0" id="6_nwl"><span style="color:#0000ff;font-size:14px;width:auto;height:auto;float:none;">block</span></a></span>-like with my siblings and we're centered in a row.

</div>

</main>

<main class="flex-center">

<div>

I'm an element that is block-like with my siblings and we're centered in a row.

</div>

<div>

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.

</div>

<div>

I'm an element that is block-like with my siblings and we're centered in a row.

</div>

</main>

body {

background: #f06d06;

font-size: 80%;

}

main {

background: white;

margin: 20px 0;

padding: 10px;

}

main div {

background: black;

color: white;

padding: 15px;

max-width: 125px;

margin: 5px;

}

.inline-<span style="width: auto; height: auto; float: none;" id="5_nwp"><a style="text-decoration: none;" mpid="5" target="_blank" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=0&is_app=0&jk=f3e358418dc3f42b&k=block&k0=block&kdi0=0&luki=2&n=10&p=baidu&q=06011078_cpr&rb=0&rs=1&seller_id=1&sid=2bf4c38d4158e3f3&ssp2=1&stid=0&t=tpclicked3_hc&tu=u1922429&u=http%3A%2F%2Fwww%2Eadmin10000%2Ecom%2Fdocument%2F5106%2Ehtml&urlid=0" id="5_nwl"><span style="color:#0000ff;font-size:14px;width:auto;height:auto;float:none;">block</span></a></span>-center {

text-align: center;

}

.inline-block-center div {

display: inline-block;

text-align: left;

}

.flex-center {

display: flex;

justify-content: center;

}

 垂直居中

  垂直居中在CSS中有点棘手

  内联元素(inline or inline-*)居中,像文本和链接那样的?

  它是一行的吗?

  有时侯元素可以表现像垂直居中,只是因为它们有相等的上下padding

  如果padding因为某些原因不能用,而且文本不会换行的情况下,你可以使用line-height,让其与height相等去对齐文本。

CSS Code

.center-text-trick {

height: 100px;

line-height: 100px;

whitewhite-space: nowrap;

}

  它是多行的?

  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,就像talbe那样

CSS Code

<table>

<tr>

<td>

I'm vertically centered multiple lines of text in a real table cell.

</td>

</tr>

</table>

<div class="center-table">

<p>I'm vertically centered multiple lines of text in a CSS-created table <span style="width: auto; height: auto; float: none;" id="4_nwp"><a style="text-decoration: none;" mpid="4" target="_blank" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=0&is_app=0&jk=f3e358418dc3f42b&k=layout&k0=layout&kdi0=0&luki=1&n=10&p=baidu&q=06011078_cpr&rb=0&rs=1&seller_id=1&sid=2bf4c38d4158e3f3&ssp2=1&stid=0&t=tpclicked3_hc&tu=u1922429&u=http%3A%2F%2Fwww%2Eadmin10000%2Ecom%2Fdocument%2F5106%2Ehtml&urlid=0" id="4_nwl"><span style="color:#0000ff;font-size:14px;width:auto;height:auto;float:none;">layout</span></a></span>.</p>

</div>

body {

background: #f06d06;

font-size: 80%;

}

table {

background: white;

width: 240px;

border-collapse: separate;

margin: 20px;

height: 250px;

}

table td {

background: black;

color: white;

padding: 20px;

border: 10px solid white;

/* default is vertical-align: middle; */

}

.center-table {

display: table;

height: 250px;

background: white;

width: 240px;

margin: 20px;

}

.center-table p {

display: table-cell;

margin: 0;

background: black;

color: white;

padding: 20px;

border: 10px solid white;

vertical-align: middle;

}

  块级元素(block level)垂直居中?

  你知道元素的高度吗?

  出于很多方面的原因,不知道网页布局的高度是相当普遍的。

  但是如果你的布局有一个固定高度,你就可以这样垂直居中:

CSS Code

.parent {

position: relative;

}

.child {

position: absolute;

top: 50%;

height: 100px;

margin-top: -50px; /* 如果没有使用: border-box; 的盒子模型则需要设置这个 */

}

  元素的高度是未知的

  尽管未知,但你仍有可能向上推移50%的宽度

CSS Code

.parent {

position: relative;

}

.child {

position: absolute;

top: 50%;

transform: translateY(-50%);

}

  你可以使用flexbox吗?

  这并不奇怪,使用flexbox会容易非常多

CSS Code

<main>

<div>
I'm a <span style="width: auto; height: auto; float: none;" id="2_nwp"><a style="text-decoration: none;" mpid="2" target="_blank" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=0&is_app=0&jk=f3e358418dc3f42b&k=block&k0=block&kdi0=0&luki=2&n=10&p=baidu&q=06011078_cpr&rb=0&rs=1&seller_id=1&sid=2bf4c38d4158e3f3&ssp2=1&stid=0&t=tpclicked3_hc&tu=u1922429&u=http%3A%2F%2Fwww%2Eadmin10000%2Ecom%2Fdocument%2F5106%2Ehtml&urlid=0" id="2_nwl"><span style="color:#0000ff;font-size:14px;width:auto;height:auto;float:none;">block</span></a></span>-level element with an unknown height, centered vertically within my parent.

</div>

</main>

body {

background: #f06d06;

font-size: 80%;

}

main {

background: white;

height: 300px;

width: 200px;

padding: 20px;

margin: 20px;

display: flex;

flex-direction: column;

justify-content: center;

resize: vertical;

overflow: <span style="width: auto; height: auto; float: none;" id="1_nwp"><a style="text-decoration: none;" mpid="1" target="_blank" href="http://cpro.baidu.com/cpro/ui/uijs.php?adclass=0&app_id=0&c=news&cf=1001&ch=0&di=128&fv=0&is_app=0&jk=f3e358418dc3f42b&k=auto&k0=auto&kdi0=0&luki=3&n=10&p=baidu&q=06011078_cpr&rb=0&rs=1&seller_id=1&sid=2bf4c38d4158e3f3&ssp2=1&stid=0&t=tpclicked3_hc&tu=u1922429&u=http%3A%2F%2Fwww%2Eadmin10000%2Ecom%2Fdocument%2F5106%2Ehtml&urlid=0" id="1_nwl"><span style="color:#0000ff;font-size:14px;width:auto;height:auto;float:none;">auto</span></a></span>;

}

main div {

background: black;

color: white;

padding: 20px;

resize: vertical;

overflow: auto;

}

 同时水平和垂直居中

  元素有固定的宽度和高度

  如果元素的宽度和高度是固定的,你需要先绝对居中,然后上移和左移50%的宽度即可,这种方案有极好的跨浏览器支持。

CSS Code

.parent {

position: relative;

}

.child {

width: 300px;

height: 100px;

padding: 20px;

position: absolute;

top: 50%;

left: 50%;

margin: -70px 0 0 -170px;

}

  元素的宽度高度未知

  如果你不知道高度和宽度(可变的),你可以使用transofrm属性在两个方向都平移负50%

CSS Code

.parent {

position: relative;

}

.child {

position: absolute;

top: 50%;

left: 50%;

transform: translate(-50%, -50%);

}

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