如何在 div 中绝对居中定位元素？

I need to place a div (with position:absolute;) element in the center of my window. But I am having problems doing so, because the width is unknown.

I tried this. But it needs to be adjusted as the width is responsive.

.center {
  left: 50%;
  bottom:5px;
}

Any ideas?

转载于:https://stackoverflow.com/questions/1776915/how-to-center-absolutely-positioned-element-in-div

<body>
  <div style="position: absolute; left: 50%;">
    <div style="position: relative; left: -50%; border: dotted red 1px;">
      I am some centered shrink-to-fit content! <br />
      tum te tum
    </div>
  </div>
</body>

</div>

As far as I know, this is impossible to achieve for an unknown width.

You could - if that works in your scenario - absolutely position an invisible element with 100% width and height, and have the element centered in there using margin: auto and possibly vertical-align. Otherwise, you'll need Javascript to do that.

Heres a useful jQuery plugin to do this. Found here. I don't think it's possible purely with CSS

/**
 * @author: Suissa
 * @name: Absolute Center
 * @date: 2007-10-09
 */
jQuery.fn.center = function() {
    return this.each(function(){
            var el = $(this);
            var h = el.height();
            var w = el.width();
            var w_box = $(window).width();
            var h_box = $(window).height(); 
            var w_total = (w_box - w)/2; //400
            var h_total = (h_box - h)/2;
            var css = {"position": 'absolute', "left": w_total+"px", "top":
h_total+"px"};
            el.css(css)
    });
};

This works for me:

#content {
  position: absolute; 
  left: 0; 
  right: 0; 
  margin-left: auto; 
  margin-right: auto; 
  width: 100px; /* Need a specific value to work */
}
<body>
  <div>
    <div id="content">
      I'm the content
    </div>
  </div>
</body>

</div>

Really nice post.. Just wanted to add if someone wants to do it with single div tag then here the way out:

Taking width as 900px.

#styleName {
    position: absolute;
    left: 50%;
    width: 900px;
    margin-left: -450px;
}

In this case one should know the width beforehand.

I'd like to add on to @bobince's answer:

<body>
    <div style="position: absolute; left: 50%;">
        <div style="position: relative; left: -50%; border: dotted red 1px;">
            I am some centered shrink-to-fit content! <br />
            tum te tum
        </div>
    </div>
</body>

Improved: /// this makes the horizontal scrollbar not appear with large elements in the centered div.

<body>
    <div style="width:100%; position: absolute; overflow:hidden;">
        <div style="position:fixed; left: 50%;">
            <div style="position: relative; left: -50%; border: dotted red 1px;">
                I am some centered shrink-to-fit content! <br />
                tum te tum
            </div>
        </div>
    </div>
</body>

I have used similar solution:

#styleName {
    position: absolute;
    margin-left: -"X"px;
}

Where "X" is half of the width of a div I want to display. Works fine for me in all browsers.

Searching for an solution I got answers above and could make content centered with Matthias Weiler answer but using text-align.

#content{
  position:absolute;
  left:0;
  right:0;
  text-align: center;
}

Worked with chrome and Firefox.

This is a trick I figured out for getting a DIV to float exactly in the center of a page. Really ugly of course, but works in all

Dots and Dashes

<div style="border: 5 dashed red;position:fixed;top:0;bottom:0;left:0;right:0;padding:5">
    <table style="position:fixed;" width="100%" height="100%">
        <tr>
            <td style="width:50%"></td>
            <td style="text-align:center">
                <div style="width:200;border: 5 dashed green;padding:10">
                    Perfectly Centered Content
                </div>
            </td>
            <td style="width:50%"></td>
        </tr>
    </table>
</div>

Cleaner

Wow that five years just flew by, didn't it?

<div style="position:fixed;top:0px;bottom:0px;left:0px;right:0px;padding:5px">
<table style="position:fixed" width="100%" height="100%">
    <tr>
        <td style="width:50%"></td>
        <td style="text-align:center">
            <div style="padding:10px">
                <img src="Happy.PM.png">
                <h2>Stays in the Middle</h2>
            </div>
        </td>
        <td style="width:50%"></td>
    </tr>
</table>

Try not to use the dark side of the CSS. Avoid using negative values for margins. I know that sometimes you are forced to do awful things like a margin-left: -450px, but probably you could do something like right: 450px. It's just my way to work.

You can place the image in a div and add a div id and have the CSS for that div have a text-align:center

HTML:

<div id="intro_img">

    <img src="???" alt="???">

</div>

CSS :

#intro_img {
    text-align:center;
}

HTML:

<div class="wrapper">
    <div class="inner">
        content
    </div>
</div>

CSS:

.wrapper {
    position: relative;

    width: 200px;
    height: 200px;

    background: #ddd;
}

.inner {
    position: absolute;
    top: 0; bottom: 0;
    left: 0; right: 0;
    margin: auto;

    width: 100px;
    height: 100px;

    background: #ccc;
}

This and more examples here

Absolute Centre

HTML :

<div class="parent">
  <div class="child">
    <!-- content -->
  </div>
</div>

CSS :

.parent {
  position: relative;
}

.child {
  position: absolute;

  top: 0;
  right: 0;
  bottom: 0;
  left: 0;

  margin: auto;
}

Demo: http://jsbin.com/rexuk/2/

Tested in Google Chrome, Firefox, and IE8

Hope this helps :)

My preferred centering method:

position: absolute;
margin: auto;
width: x%
  • absolute block element positioning
  • margin auto
  • same left/right, top/bottom

JSFiddle here

Responsive Solution

Here is a good solution for responsive design or unknown dimensions in general if you don't need to support IE8 and lower.

.centered-axis-x {
    position: absolute;
    left: 50%;
    transform: translate(-50%, 0);
}


.outer {
    position: relative; /* or absolute */
    
    /* unnecessary styling properties */
    margin: 5%;
    width: 80%;
    height: 500px;
    border: 1px solid red;
}

.inner {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    
    /* unnecessary styling properties */
    max-width: 50%;
    text-align: center;
    border: 1px solid blue;
}
<div class="outer">
    <div class="inner">I'm always centered<br/>doesn't matter how much text, height or width i have.<br/>The dimensions or my parent are irrelevant as well</div>
</div>

Here is a JS Fiddle

The clue is, that left: 50% is relative to the parent while the translate transform is relative to the elements width/height.

This way you have a perfectly centered element, with a flexible width on both child and parent. Bonus: this works even if the child is bigger than the parent.

You can also center it vertically with this (and again, width and height of parent and child can be totally flexible (and/or unknown)):

.centered-axis-xy {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%,-50%);
}

Keep in mind that you might need transform vendor prefixed as well. For example -webkit-transform: translate(-50%,-50%);

</div>

#container
{
  position: relative;
  width: 100%;
  float:left
}
#container .item
{
  width: 50%;
  position: absolute;
  margin: auto;
  left: 0;
  right: 0;
}

HTML

<div id='parent'>
  <div id='centered-child'></div>
</div>

CSS

#parent {
  position: relative;
}
#centered-child {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
  margin: auto auto;
}

http://jsfiddle.net/f51rptfy/

this work for vertical and horizontal

  #myContent{
        position: absolute;
        left: 0;
        right: 0;
        top:0;
        bottom:0;
        margin: auto;
   }

and if you want make element center of parent, set position of parent relative

 #parentElement{
      position:relative
  }

edit:

  • for vertical center align set height to your element. thanks to @Raul

  • if you want make element center of parent, set position of parent to relative

I know I already provided an answer, and my previous answer, along with others given, work just fine. But I have used this in the past and it works better on certain browsers and in certain situations. So I thought id give this answer as well. I did not "Edit" my previous answer and add it because I feel this is an entirely separate answer and the two I have provided are not related.

HTML:

<div id='parent'>
  <div id='child'></div>
</div>

CSS:

#parent {
  display: table;
}
#child {
  display: table-cell;
  vertical-align: middle;
}

sass/compass version of Responsive Solution above:

#content {
  position: absolute;
  left: 50%;
  top: 50%;
  @include vendor(transform, translate(-50%, -50%));
}

This worked for me :

<div class="container><p>My text</p></div>

.container{
position: absolute;
left: 0;
right: 0;
margin-left: auto;
margin-right: auto;
}


#content { margin:0 auto; display:table; float:none;}
<body>
  <div>
    <div id="content">
      I'm the content
    </div>
  </div>
</body>

</div>

I understand this question already has a few answers, but I've never found a solution that would work in almost all classes that also makes sense and is elegant, so here's my take after tweaking a bunch:

.container {
    position: relative;
}

.container .cat-link {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate3d(-50%,-50%,0);
    z-index: 100;
    text-transform: uppercase; /* Forces CSS to treat this as text, not a texture, so no more blurry bugs */
    background-color: white;
}

.color-block {
  height: 250px;
  width: 100%;
  background-color: green;
}
<div class="container">
  <a class="cat-link" href="">Category</a>
  <div class="color-block"></div>
</div>

What this does is saying give me a top: 50% and a left: 50%, then transform (create space)on both the X/Y axis to the -50% value, in a sense "create a mirror space".

As such, this creates an equal space on all the 4 points of a div, which is always a box (has 4 sides).

This will:

  1. Work without having to know the parent's height / width.
  2. Work on responsive.
  3. Work on either X or Y axis. Or both, as in my example.
  4. I can't come up with a situation where it doesn't work.
</div>

A simple approach that worked for me to horizontally center a block of unknown width:

<div id="wrapper">
  <div id="block"></div>
</div>

#wrapper { position: absolute; width: 100%; text-align: center; }
#block { display: inline-block; }

A text-align property may be added to the #block ruleset to align its content independently of the alignment of the block.

This worked on recent versions of Firefox, Chrome, IE, Edge and Safari.

Works on any random unknown width of the absolute positioned element you want to have in the centre of your container element.

Demo

<div class="container">
  <div class="box">
    <img src="https://picsum.photos/200/300/?random" alt="">
  </div>
</div>

.container {
  position: relative;
  width: 100%;
}

.box {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  display: flex;
  justify-content: center;
  align-items: center;
}

This solution works if the element has width and height

.wrapper {
  width: 300px;
  height: 200px;
  background-color: tomato;
  position: relative;
}

.content {
  width: 100px;
  height: 100px;
  background-color: deepskyblue;
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  margin: auto;
}
<div class="wrapper">
  <div class="content"></div>
</div>

</div>