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Asked: 2026-06-14T23:54:05+00:00

I would like to create a content panel that is in the absolute middle

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I would like to create a content panel that is in the absolute middle of the page. It can expand both its width and height to a certain percent of the page before scrollbars appear.

I am using Primefaces on a JSF page. I am sure there are many solutions out there to do this. I would like to use JSF’s composition.

Here is my solution:

<p:layout id="layout">
        <p:layoutUnit position="center">
            <p:panel header="Test" style="width:50%">
                <ui:insert name="content"/>
            </p:panel>
        </p:layoutUnit>
    </p:layout>

However, this doesn’t really do anything. Its not centered, what ever I insert into the “content” tag expands to the whole page.

Can anyone assist on how I might accomplish my goal?

EDIT

I have tried the solution posted by Rick Calder. Below is my code. It however does not work for me. I wrote the css into the style.css. I wrote the javascript into resizeContentPanel.js. I load JQUery and the resizeContentPanel.js in the head of my resource.xhtml. I believe these are all the correct steps. Is there anything I could be missing.

As for what i actually wrong, I do not see the content panel. When I debug the javascript, it has a height-margin of -71 and a width-margin of -160. I am assuming this is why I cant see it.

<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
  xmlns:h="http://java.sun.com/jsf/html"
  xmlns:ui="http://java.sun.com/jsf/facelets"
  xmlns:p="http://primefaces.org/ui"
  xmlns:f="http://java.sun.com/jsf/core">
<h:head>
    <title>
        <ui:insert name="windowTitle"/>
    </title>

    <h:outputStylesheet library="css" name="style.css"/>
    <script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.2/jquery.min.js"></script>
    <h:outputScript library="scripts" name="resizeContentPanel.js" />
</h:head>
<h:body>
    <div class="centeredPanel">
        <p:layout id="layout" >
            <p:layoutUnit position="center">
                <ui:insert name="content"/>
            </p:layoutUnit>
        </p:layout>
    </div>

    <h:form>
        <div id="stack">
            <p:stack id="stackMenu" icon="/resources/images/stack/stack.png" model="#{pageBuilder.stackMenuModel}" /> 
        </div>
    </h:form>

    <div id="dock">
        <p:dock id="dockMenu" model="#{pageBuilder.dockMenuModel}"/>
    </div>

</h:body>

style.css

root 
{ 
    display: block;
}

body
{
    background-image: url('../../resources/images/background/background.jpg');
}

.centeredPanel{
    width:25%;
    height:25%;
    min-width:100px;
    min-height:100px;
    position:absolute;
    left:50%;
    top:50%;
}​

resizeContentPanel.js

$(document).ready(function(){
var heightMargin =  -($('.centeredPanel').height()/2);
var widthMargin=  -($('.centeredPanel').width()/2);
$('.centeredPanel').css('margin-left',widthMargin);
$('.centeredPanel').css('margin-top',heightMargin);
});

$(window).resize(function(){
var heightMargin =  -($('.centeredPanel').height()/2);
var widthMargin=  -($('.centeredPanel').width()/2);
$('.centeredPanel').css('margin-left',widthMargin);
$('.centeredPanel').css('margin-top',heightMargin);
});
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1 Answer

  1. Editorial Team

    To perfectly centre something in the page you really want it to be a fixed size so you can do the calculations.

    .centeredPanel{
    width:500px;
    height:500px;
    position:absolute;
    left:50%; //sets left edge at the midway point of it's container
    top:50%; //sets top edge at the midway point of it's container
    margin-left:-250px; //moves the div back half it's width to centre it.
    margin-top:-250px; //moves the div up half it's height to centre it.
}

    Demo: http://jsfiddle.net/calder12/qNNvb/

    To do it with percentages requires jQuery.

    .centeredPanel{
    width:25%;
    height:25%;
    min-width:100px;
    min-height:100px;
    position:absolute;
    left:50%;
    top:50%;
    background-color:red;
}​


$(document).ready(function(){
var heightMargin =  -($('.centeredPanel').height()/2);
var widthMargin=  -($('.centeredPanel').width()/2);
$('.centeredPanel').css('margin-left',widthMargin);
$('.centeredPanel').css('margin-top',heightMargin);
});

$(window).resize(function(){
var heightMargin =  -($('.centeredPanel').height()/2);
var widthMargin=  -($('.centeredPanel').width()/2);
$('.centeredPanel').css('margin-left',widthMargin);
$('.centeredPanel').css('margin-top',heightMargin);
});

    Demo: http://jsfiddle.net/calder12/qNNvb/3/

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