CSS：居中相对div问题中的绝对位置
[英]CSS: absolute position inside centered relative div issue
问题描述
I have an issue with absolute and relative positioning. 
我对绝对和相对定位有疑问。
Im trying to center a relative DIV that contains all absolute div. 我试图居中包含所有绝对div的相对DIV。 The problem I have is when I try to center my relative DIV, my absolute div "#mainForm" get shrink (height issue). 我遇到的问题是，当我尝试将相对DIV居中时，我的绝对div“ #mainForm”缩小（高度问题）。
In the html below, if you remove the position and margin attribute on the "#main" class, you will see that the page layout is displayed correctly. 在下面的html中，如果删除“ #main”类上的position和margin属性，则会看到页面布局显示正确。
How can I center my relative div without affecting my absolute divs ? 如何在不影响绝对div的情况下居中相对div？
** What im trying to achieve is to have only my #mainForm that is scrollable. 我试图实现的是仅使我的#mainForm可滚动。 My sideBar, mainHeader and mainFooter must be "fixed". 我的sideBar，mainHeader和mainFooter必须“固定”。 Client requirements... 客户要求...
Thanks David 谢谢大卫
Here is my CSS and HTML. 这是我的CSS和HTML。
- xhtml11.dtd doctype. xhtml11.dtd文档类型。
<head>
<meta http-equiv="content-type" content="text/html;charset=iso-8859-1" />
<style>
html {
box-sizing: border-box;
}
body {
font-family: Helvetica,Arial,sans-serif;
font-size: 8pt;
}
*, *:before, *:after {
box-sizing: inherit;
}
#main {
position: relative; /* if I removed this, page is not centered but mainForm height is ok */
margin: 0 auto; /* if I removed this, page is not centered but mainForm height is ok */
width: 960px;
}
#sideBar {
position: absolute;
top:0;
bottom:0;
left:0;
width: 180px;
}
#mainContent {
position: absolute;
top:0;
bottom:0;
right:0;
left:180px; /* Width of #sideBar. */
width: 780px;
}
#mainHeader {
position: absolute;
top:0;
height:40px;
width:100%; /* Mandatory. With is 100% of parent div. */
border: 1px solid blue; /* For developing purpose */
}
#mainForm {
position: absolute;
overflow:auto;
top:40px;
bottom:40px;
width:100%; /* Mandatory. With is 100% of parent div. */
border: 1px solid yellow; /* For developing purpose */
}
#mainFooter {
position: absolute;
bottom:0;
height:40px;
text-align:right;
width:100%; /* Mandatory. With is 100% of parent div. */
}
#topSideBar {
position: absolute;
top:0;
left:0;
background-image: url("../images/pas/contactLogo.png");
background-repeat: no-repeat;
height:110px;
width:100%; /* Mandatory. With is 100% of parent div. */
}
#middleSideBar {
position: absolute;
top:110px;
height:200px;
width:100%; /* Mandatory. With is 100% of parent div. */
}
#bottomSideBar {
position: absolute;
bottom:0;
height:100px;
width:100%; /* Mandatory. With is 100% of parent div. */
}
/* clearfix */
.clearFixaa:after {
content: ".";
display: block;
clear: both;
visibility: hidden;
line-height: 0;
height: 0;
}
</style>
</head>
<body>
<div id="main" class="clearFix">
<div id="sideBar" >
<div id="topSideBar">
<!-- Contact Logo css backgound. -->
</div>
<div id="middleSideBar">
middleSideBar
</div>
<div id="bottomSideBar">
bottomSideBar
</div>
</div>
<div id="mainContent">
<div id="mainHeader">
mainHeader
</div>
<div id="mainForm">
<br/><br/><br/><br/><br/><br/><br/><br/><br/>
mainForm
<br/><br/><br/><br/><br/><br/><br/><br/><br/>
<br/><br/><br/><br/><br/><br/><br/><br/><br/>
mainForm
<br/><br/><br/><br/><br/><br/><br/><br/><br/>
<br/><br/><br/><br/><br/><br/><br/><br/><br/>
mainForm
<br/><br/><br/><br/><br/><br/><br/><br/><br/>
<br/><br/><br/><br/><br/><br/><br/><br/><br/>
mainForm
<br/><br/><br/><br/><br/><br/><br/><br/><br/>
<br/><br/><br/><br/><br/><br/><br/><br/><br/>
mainForm
<br/><br/><br/><br/><br/><br/><br/><br/><br/>
</div>
<div id="mainFooter">
mainFooter
</div>
</div>
</div>
</body>
1 个解决方案
解决方案1
0 已采纳 2015-05-07 14:52:47
I modified your css. 我修改了您的CSS。 This will do the work: 这将完成工作：
html {
box-sizing: border-box;
}
body {
font-family: Helvetica, Arial, sans-serif;
font-size: 8pt;
}
*, *:before, *:after {
box-sizing: inherit;
}
#main {
position: fixed;
/* if I removed this, page is not centered but mainForm height is ok */
margin: 0 auto;
/* if I removed this, page is not centered but mainForm height is ok */
width: 960px;
height: 960px;
left: 0;
right: 0;
}
#sideBar {
position: absolute;
top:0;
bottom:0;
left:0;
width: 180px;
border: 1px solid red;
/* For developing purpose */
}
#mainContent {
position: absolute;
top:0;
bottom:0;
right:0;
left:180px;
/* Width of #sideBar. */
width: 780px;
height: 100%;
}
#mainHeader {
position: absolute;
top:0;
height:40px;
width:100%;
/* Mandatory. With is 100% of parent div. */
border: 1px solid blue;
/* For developing purpose */
}
#mainForm {
position: absolute;
overflow:auto;
top:40px;
bottom:40px;
width:100%;
/* Mandatory. With is 100% of parent div. */
border: 1px solid yellow;
/* For developing purpose */
}
#mainFooter {
position: absolute;
bottom:0;
height:40px;
text-align:right;
width:100%;
/* Mandatory. With is 100% of parent div. */
}
#topSideBar {
position: absolute;
top:0;
left:0;
background-image: url("../images/pas/contactLogo.png");
background-repeat: no-repeat;
height:110px;
width:100%;
/* Mandatory. With is 100% of parent div. */
}
#middleSideBar {
position: absolute;
top:110px;
height:200px;
width:100%;
/* Mandatory. With is 100% of parent div. */
}
#bottomSideBar {
position: absolute;
bottom:0;
height:100px;
width:100%;
/* Mandatory. With is 100% of parent div. */
}
/* clearfix */
.clearFixaa:after {
content:".";
display: block;
clear: both;
visibility: hidden;
line-height: 0;
height: 0;
}
The trick was to fixed the #main div and position it with left:0 and right:0. 诀窍是固定#main div并将其定位为left：0和right：0。 I had a static height for the main div, feel free to remove it and add height where you need like for the sidebar. 我的主要div高度为静态，可以随时将其删除，并在需要的地方添加高度，例如侧边栏。
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