The border-bottom-width property (CSS Reference)
Introduction
This property is used to set the width of the bottom border.
The following example demonstrates the bottom border in a wider width than the
others.
Example
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><title>border-bottom-width
Demonstration</title>
<style type="text/css">
p.border
{
border-left-width:3px;
border-left-color:black;
border-left-style:solid;
border-right-width:3px;
border-right-color:Black;
border-right-style:solid;
border-top-width:3px;
border-top-color:Black;
border-top-style:solid;
border-bottom-width:10px;
border-bottom-color:red;
border-bottom-style:solid;
}
</style>
</head>
<body>
<h1><p class="border">The width of the
bottom border should wider than the others.</p></h1>
</body>
</html>
Output

Values
|
Name:
|
Description:
|
|
length
|
The following values can be also used to define the bottom
border width:
cm (centimeter)
em (ems)
inch (inches)
mm (millimeters)
pc (picas)
px (pixels)
pt (points)
|
|
medium
|
This value creates a border with a medium width.
|
|
thick
|
This value creates a thick border.
|
|
thin
|
This value creates a border with a thin width.
|
|