HTML and CSS Reference
In-Depth Information
</body>
</html>
<blockquote cite=
'http://www.gutenberg.org/dirs/etext00/dvlft10.txt'>
<p>
It was, then, with <em>considerable</em> surprise that I
received a telegram from Holmes last Tuesday—he has
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>3 Column Page</title>
<link rel="stylesheet" href="threecolumns.css"
type="text/css" />
</head>
<body>
<div id="Left">
Left column content
</div>
<div id="Center">
Center column content
</div>
<div id="Right">
Right column content
</div>
</body>
</html>
Motivation
CSS layouts are more powerful and more accessible than table layouts. They work better across a broader
variety of devices, such as PDAs and audio browsers. They are more understandable to machines and thus
enable better processing of content, including somewhat enhanced search engine optimization. Finally, they
make it easier to edit and update pages both because the pages are simpler and because the style and content
are separated so that designers don't step on authors' toes and vice versa.
CSS-based pages are smaller and simpler than table-based pages. This makes them easier to edit and easier to
author. It also makes them faster to download. All those
<td>
and
<tr>
tags add up. A kilobyte here, a kilobyte
there, and pretty soon you're talking about real bandwidth. High-volume sites such as Slashdot can save
gigabytes per day and thousands of dollars in bandwidth costs per year by moving to CSS. Although the CSS
files themselves take some bandwidth, they can be cached and reused. They do not need to be downloaded with
every page.
Potential Trade-offs
CSS layouts do tend to fix sizes more than table layouts do. For example, with tables it is possible to define a
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