Rounded Corners on DIVs with Background Color

Another way to accomplish this was to set the outer div to have a overflow to hidden

#shell {
 width:500px;
 height:300px;
 background:lightGrey; 
 border-radius: 10px 10px 10px 10px;
 overflow:hidden;
}
#title {
 background:green;
 padding:5px;
}

http://jsfiddle.net/jdaines/NaxuK/

In your markup, you have to give border-radius to both #shell and #title so that the #title's sharp corners don't overlap #shell's.

A live example, http://jsfiddle.net/BXSJe/4/

#shell {
  width: 500px;
  height: 300px;
  background: lightGrey;
  border-radius: 6px;
}

#title {
  background: green;
  padding: 5px;
  border-radius: 6px 6px 0 0;
}

<div id="shell">
  <div id="title">TITLE HERE</div>
  <div id="content">Article Content Goes Here</div>
</div>