The border-width CSS property sets the width of the border of a box. Using the shorthand property border is often more convenient.
Values
<br-width>
Is either a non-negative explicit <length> value or a keyword denoting the thickness of the bottom border. The keyword must be one of the following values:
| thin | A thin border | |
| medium | A medium border | |
| thick | A thick border |
Example
<!DOCTYPE HTML>
<html>
<head>
<title>CSS Tutorials</title>
<style>
div {
border: solid red;
/* 2px wide top and bottom border, 10px right and left border */
border-width: 2px 10px;
}
</style>
</head>
<body>
<div>
Border-Width Demonstration
</div>
</body>
</html>