i hope you are looking like this........... see the DEMO
UPDATED DEMO 2 AS PER YOUR CURRENT REQUIREMENTS
CSS
.parent {
background:red;
width:900px;
margin:0 auto;
padding:10px;
-moz-box-sizing:border-box;
-webkit-box-sizing:border-box;
box-sizing:border-box;
}
.inner {
background:green;
height:100px;
position:absolute;
left:0;
right:0;
}
.child {
height:100px;
background:black;
margin:10px 0;
}
-------------**
Second Answer with without positioning but with a some trick what i used here so please check it the code & demo mentioned below :-
HTML
<body>
<div class="parent"> /** Width:900px; **/
<div class="child"></div>
</div>
<div class="inner"> /** This I want 100% of BODY, not of parent div **/</div>
<div class="parent">
<div class="child"></div>
<div class="child"></div>
</div>
</body>
CSS
.parent {
background:red;
width:900px;
margin:0 auto;
padding:10px;
-moz-box-sizing:border-box;
-webkit-box-sizing:border-box;
box-sizing:border-box;
}
.inner {
background:green;
height:100px;
}
.child {
height:100px;
background:black;
margin:10px 0;
}
DEMO
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
