box-shadow

Last updated on: January 9, 2012

Used in casting shadows (often called "Drop Shadows" like in Photoshop). Using them

.shadow {
  -webkit-box-shadow: 3px 3px 5px 6px #ccc;  /* Safari 3-4, iOS 4.0.2 - 4.2, Android 2.3+ */
  -moz-box-shadow:    3px 3px 5px 6px #ccc;  /* Firefox 3.5 - 3.6 */
  box-shadow:         3px 3px 5px 6px #ccc;  /* Opera 10.5, IE 9, Firefox 4+, Chrome 6+, iOS 5 */
}

1. The horizontal offset (required) of the shadow, positive means the shadow will be on the right of the box, a negative offset will put the shadow on the left of the box.
2. The vertical offset (required) of the shadow, a negative one means the box-shadow will be above the box, a positive one means the shadow will be below the box.
3. The blur radius (optional), if set to 0 the shadow will be sharp, the higher the number, the more blurred it will be.
4. The spread radius (optional), positive values increase the size of the shadow, negative values decrease the size. Default is 0 (the shadow is same size as blur).
5. Color (required) - takes any color value, like hex, named, rgba or hsla.

Using a semi-transparent color like rgba(0,0,0,0.4) is most common, and a nice effect, as it doesn't completely/opaquely cover what it's over, but allows what's underneath to show through a bit, like a real shadow.

Example

Inner Shadow

.shadow {
   -moz-box-shadow:    inset 0 0 10px #000000;
   -webkit-box-shadow: inset 0 0 10px #000000;
   box-shadow:         inset 0 0 10px #000000;
}

Example

Internet Explorer (8 and down) Box Shadow

You need an extra element, but it's do-able with filter.

<div class="shadow1">
	<div class="content">
		Box-shadowed element
	</div>
</div>

.shadow1 {
	margin: 40px;
	background-color: rgb(68,68,68); /* Needed for IEs */

	-moz-box-shadow: 5px 5px 5px rgba(68,68,68,0.6);
	-webkit-box-shadow: 5px 5px 5px rgba(68,68,68,0.6);
	box-shadow: 5px 5px 5px rgba(68,68,68,0.6);

	filter: progid:DXImageTransform.Microsoft.Blur(PixelRadius=3,MakeShadow=true,ShadowOpacity=0.30);
	-ms-filter: "progid:DXImageTransform.Microsoft.Blur(PixelRadius=3,MakeShadow=true,ShadowOpacity=0.30)";
	zoom: 1;
}
.shadow1 .content {
	position: relative; /* This protects the inner element from being blurred */
	padding: 100px;
	background-color: #DDD;
}

One-Side Only

Using a negative spread radius, you can get squeeze in a box shadow and only push it off one edge of a box.

.one-edge-shadow {
	-webkit-box-shadow: 0 8px 6px -6px black;
	   -moz-box-shadow: 0 8px 6px -6px black;
	        box-shadow: 0 8px 6px -6px black;
}

Relevant Links

• CSS3: spread value and box-shadow on one side only
• Mozilla Docs
• Multiple Borders with box-shadow.

Browser Support

See snippet at top of page for specifics on vendor prefix coverage. This is one of those properties where dropping the prefixes is pretty reasonable at this point (Jan 2012).