How to make a 3D banner overlay (??) with CSS - css

Question

I want to create a banner that goes over part of the page, I'm probably not using the correct terminology...
I've seen this on more and more websites, but while trying to find website using this I've struggled to find ones to inspect. But I did find one interesting example.
http://www.bmbw.com
-Their header logo is larger than the rest of the content, with the bottom two edges angled in.
-Their "BMBW Updates" and "BMBW Snow Report" also have this effect on their respective edges.
This is the style I'm trying to do, but I was curious about the best way to do this.
The Updates, Snow Report, and Navigation (to make the header look 3d) have the effect built into the image.
But I've also seen the effect diagonally and it didn't interfere with functionality. I guess I'm just asking if there is another way to do this other than build it into the image itself.
Any Ideas?

Answer 1

You can actually accomplish this sort of effect without any images whatsoever using the CSS triangle hack. I've created a jsFiddle with a working example: http://jsfiddle.net/P8W7F/

Answer 2

CSS gradients and shadows are a good way to do it if you're using CSS3

Answer 3

I looked at their page, but they have done it with an image.
The most simple way is to have a second div with a thick top border. If you have this html:
<div class="banner">first content</div>
<div class="shadow_simple"></div>
<div class="next_content">next content block</div>
Then this css will do:
.banner {
width: 400px;
margin:auto;
text-align:center;
background-color:#eee8aa;
}
.shadow_simple {
margin:auto;
width: 360px;
height:12px;
border-top: 12px solid #daa520;
border-left: 20px solid white;
border-right: 20px solid white;
border-bottom: none;
}
.next_content {
width: 360px;
margin:auto;
text-align:center;
background-color:#eee8aa;
border: 1px solid #daa520;
margin-top:-24px;
}
The same, but with gradient triangles:
<div class="banner">first content</div>
<div class="shadow_gradient">
<div class="shadow_simple"></div>
</div>
<div class="next_content">next content block</div>
And the css:
.banner {
width: 400px;
margin:auto;
text-align:center;
background-color:#eee8aa;
}
.shadow_simple {
margin:auto;
width: 360px;
height:12px;
border-top: 12px solid transparent;
border-left: 20px solid white;
border-right: 20px solid white;
border-bottom: none;
}
.shadow_gradient {
width: 400px;
height:24px;
margin:auto;
margin-bottom:12px;
box-shadow: inset 0px 5px 12px #daa520;
}
.next_content {
width: 360px;
margin:auto;
text-align:center;
background-color:#eee8aa;
margin-top:-36px;
border:1px solid #daa520
}