Specifically, I am referring to a situation where you need to have a total width of say 100% on a DIV, but a 10 pixel padding and 1 pixel border. (And don't rely on the browser automatically setting it to that width — say it's floated left for instance.)
Is there any simple way to accomplish this without using JavaScript?
No, there's no way to set this on one element that works with the currently major browsers.
You could use 2 nested divs. Set the 100% width on the outher div, and set the padding and border on the inner div.
What about the following solution?
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Content with Menu</title>
<style type="text/css">
.content .outer{
width:100%;
border:1px solid black;
background-color:green;
}
.content .inner{
margin-left:10px;
margin-right:10px;
background-color:red;
}
</style>
</head>
<body>
<div class="content">
<div class="outer">
<div class="inner">
<p>Hi!</p>
</div>
</div>
</div>
</body>
</html>
Update OK, doesn't accomplish what you are talking about with just one element.
If you use box-sizing: border-box you can set width: 100%; border: 1px solid black; padding: 10px; and the total of the width, border, margin, and padding will be what is specified for the width. Source
EDIT: True, browser support is a bit limited. FF 3.5 and Safari 4 support it, not sure about IE8 or Chrome.