How to center absolutely positioned element in div?

问题

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?

回答1:

<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>

回答2:

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>

回答3:

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%);

回答4:

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.

回答5:

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 :)

回答6:

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

回答7:

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.

回答8:

If you need to center horizontally and vertically too:

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

回答9:

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:

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

回答10:

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;
}

回答11:

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.

回答12:

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>

回答13:

This is a mix of other answers, which worked for us:

.el {
   position: absolute;
   top: 50%;
   margin: auto;
   transform: translate(-50%, -50%);
}

回答14:

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)
    });
};

回答15:

My preferred centering method:

position: absolute;
margin: auto;
width: x%

absolute block element positioning
margin auto
same left/right, top/bottom

JSFiddle here

回答16:

sass/compass version of Responsive Solution above:

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

回答17:

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;
}

回答18:

Flex can be used to center absolute positioned div.

display:flex;
align-items:center;
justify-content:center;

.relative {
  width: 275px;
  height: 200px;
  background: royalblue;
  color: white;
  margin: auto;
  position: relative;
}

.absolute-block {
  position: absolute;
  height: 36px;
  background: orange;
  padding: 0px 10px;
  bottom: -5%;
  border: 1px solid black;
}

.center-text {
  display: flex;
  justify-content: center;
  align-items: center;
  box-shadow: 1px 2px 10px 2px rgba(0, 0, 0, 0.3);
}

<div class="relative center-text">
  Relative Block
  <div class="absolute-block center-text">Absolute Block</div>
</div>

回答19:

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;
}

回答20:

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

回答21:

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/

回答22:

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>

回答23:

the solution of this question didn't work for my case.. I'm doing a caption for some images and I solved using this

top: 0;
left: 0;
right: 0;
margin-left: auto;
margin-right: auto;

display: flex;
align-items: center;

figure {
  position: relative;
  width: 325px;
  display: block
}


figcaption{
   
    position: absolute;
    background: #FFF;
    width: 120px;
    padding: 20px;

    -webkit-box-shadow: 0 0 30px grey;
    box-shadow: 0 0 30px grey;
    border-radius: 3px;
    display: block;
    
    top: 0;
    left: 0;
    right: 0;
    margin-left: auto;
    margin-right: auto;
    
    display: flex;
    align-items: center;
}

<figure>
  <img  src="https://picsum.photos/325/600">
  <figcaption> 
			But as much
    </figcaption>
                
</figure>

回答24:

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

回答25:

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>

回答26:

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

.center:before {
    content: '';
    display: inline-block;
    margin-left: -50%;
}

回答27:

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;
}

回答28:

#content { margin:0 auto; display:table; float:none;}

<body>
  <div>
    <div id="content">
      I'm the content
    </div>
  </div>
</body>

回答29:

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.

回答30:

You can also create the middleware div#centered box centered with absolute, left and right properties and without width property and then set the main content div as its child with display:inline-block box and center it with text-align:center set for its middleware parent box

#container{
  position: relative;
  width: 300px;
  height: 300px;
  border: solid 1px blue;
  color:#dddddd;
}

#centered{
  position: absolute;
  text-align: center;
  margin: auto;
  top: 20px;
  left:0;
  right:0;
  border: dotted 1px red;
  padding: 10px 0px;
  
  
}

#centered>div{
  border: solid 1px red;
  display:inline-block;
  color:black;
}

<div id="container">
  hello world hello world
  hello world hello world
  hello world hello world
  hello world hello world
  hello world hello world
  hello world hello world
  hello world hello world
  hello world hello world
  
  <div id="centered">
    <div>
      hello world <br/>
      I don't know my width<br/>
      but I'm still absolute!  
    </div>
  </div>

</div>

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

标签

css

css-position

center

absolute