place a div upon another div - html

Question

here is my how i want the website design to be :
so i am in the initial step, my query is how do i place the slider div upon the header div and i want it to be in the centre. my code what i have used is :
<div id="header">
<div class="slider">
</div>
</div>
<div class="content">
</div>
<div class="footer">
</div>
body {
margin:0px;
padding:0px;
background:#fff;
}
#header
{
background:#859685;
height:300px;
}
.slider
{
margin-left:auto;
margin-right:auto;
margin-top:50px;
position:absolute;
z-index:1;
width:980px;
height:200px;
border: 4px #666 solid;
}
.content
{
margin-left: auto;
margin-right: auto;
margin-bottom:10px;
margin-top:10px;
width:980px;
height:400px;
background:#fff;
-moz-border-radius: 3px;
-webkit-border-radius: 3px;
border-radius: 3px;
}
.footer
{
margin-top:10px;
margin-bottom:10px;
padding: 0;
height:300px;
background:#98AFC7;
-moz-border-radius: 3px;
-webkit-border-radius: 3px;
border-radius: 3px;
background:#111312;
}
here is my fiddle jsfiddle.net/hdmep/
Thanx in advance!

Answer 1

Change your slider class to something like this:
.slider
{
margin-left:auto;
margin-right:auto;
left:0;
right:0;
margin-top:250px;
position:absolute;
width:980px;
height:200px;
border: 4px #666 solid;
}

Answer 2

Check out this Working Fiddle
I changed the sizes a little bit (so it'll look nice in the Fiddle)
this is all about absolute positioning.
also if you're just going to use background for color, use background-color instead of background
and, notice the short way of using margin for all sides at once.
CSS:
#header
{
background-color: #859685;
height: 100px;
position: relative; /*the slider is now relative to the header*/
}
.slider
{
position:absolute;
width: 80%; /*80% of header*/
height: 50%; /* 50% of header*/
border: 4px #666 solid;
top: 70%;
left: 10%;
}
.content
{
margin: 10px auto;
height: 100px;
background-color: azure;
-moz-border-radius: 3px;
-webkit-border-radius: 3px;
border-radius: 3px;
}
.footer
{
margin: 10px 0;
height: 100px;
-moz-border-radius: 3px;
-webkit-border-radius: 3px;
border-radius: 3px;
background-color: #111312;
}

Answer 3

try this:
DEMO
update slider class:
.slider {
margin-left: auto;
margin-right: auto;
bottom: -150px;
position: relative;
z-index: 1;
width: 980px;
height: 200px;
border: 4px #666 solid;
}