Multiple Divs / Classes On an Opaque Background - css

Question

My goal (and the question of how-to) is to have an opaque / white background with black fields over the opaque area to serve as content holders. Here is what I have now:
/* translucent background*/
.background
{
width:950px;
height:1024px;
margin: 9px auto 10px;
background-color:#ffffff;
opacity:0.35;
filter:alpha(opacity=35); /* For IE8 and earlier */
border-radius: 15px;
-moz-border-radius: 15px;
z-index:0;
}
/*content wrapper*/
.content
{
font-family: Arial;
font-size: 11px;
width:950px;
height:1024px;
margin: 9px auto 10px;
border-radius: 15px;
-moz-border-radius: 15px;
z-index:1;
}
/*one of three content fields*/
.anounce_bar
{
font-family: Arial;
font-size: 16px;
width:940px;
height:225px;
float: left;
border: 5px 5px 5px 5px;
background-color: black;
border-radius: 15px;
-moz-border-radius: 15px;
z-index:2;
}
<div class="background"></div>
<div class="content">
<!--Top announcement bar-->
<div class="anounce_bar">
</div>
<!--Left side nav bar-->
<div class="nav" style="height: 1024px; ">
</div>
<!--Right side content window-->
<div class="content_window">
</div>
</div>
Right now its showing the anounce_bar below the translucent background.. how do I get the bar (and subsequent nav & content_window) to go on top of .background?
Note: I have other content, including a top 'masthead' image and a background JPG that might be screwing with this.
Any help would be GREATLY appreciated.
Update:
This was an issue with opacity inheritance - the work around I used is described very well here
'background' class became #background without any opacity, and a new item was added:#background .transparency with absolute positioning and opacity.
<div id="background">
<div class='transparency'></div>
/*OTHER STUFF*/
</div>

Answer 1

Change the order
<div class="anounce_bar"></div>
<div class="background"></div>
That should work.

Answer 2

<div class="background">
<div class="content">
<!--Top announcement bar-->
<div class="anounce_bar" style="color: white">Anounce Bar</div>
<!--Left side nav bar-->
<div class="nav" style="height: 24px; width: 940px; background-color: green; float:left;">Nav</div>
<!--Right side content window-->
<div class="content_window" style="height: 24px; width: 940px; background-color: yellow; float:left;">Content Window</div>
</div>
</div>
Sample Code