HTML and CSS Reference
In-Depth Information
H.3. Layers
Spacers and multiple columns are natural extensions to conventional
HTML, existing within a document's normal flow. With version 4, Nets-
cape took HTML into an entirely new dimension with layers. It transforms
the single-element document model into one containing many layered
elements that are combined to form the final document. Regrettably, lay-
ers are not supported by Netscape 6 or any version of Internet Explorer.
Layers supply the layout artist with a critical element missing in standard
HTML: absolute positioning of content within the browser window. Layers
let you define a self-contained unit of HTML content that can be posi-
tioned anywhere in the browser window, placed above or below other
layers, and made to appear and disappear as you desire. Document lay-
outs that were impossible with conventional HTML are trivial with layers.
If you think of your document as a sheet of paper, layers are like sheets
of clear plastic placed on top of your document. For each layer, you
define the content of the layer, its position relative to the base document,
and the order in which it is placed on the document. Layers can be trans-
parent or opaque, visible or hidden, providing an endless combination of
layout options.
H.3.1. The <layer> Tag (Antiquated)
Each HTML document content layer is defined with the
<layer>
tag. A lay-
er can be thought of as a miniature HTML document whose content is
defined between the
<layer>
and
</layer>
tags. Alternatively, the content
of the layer can be retrieved from another HTML document by using the
src
attribute with the
<layer>
tag.
