border-width | NN 4 IE 4 CSS 1
| Inherited: No
This is a shortcut attribute that lets you set multiple border edges to the same or different widths. You may supply one to four space-delimited width length values. The number of values determines which sides receive the assigned widths.
CSS Syntax
    border-width: thin | medium | thick | length {1,4}
Value
Three constantsthin | medium | thickallow the browser to define how many pixels are used to show the border. For more precision, you can also assign a length value (see the discussion of length values at the beginning of this chapter). This attribute accepts one, two, three, or four space-delimited borderWidth values, depending on how many and which borders you want to set with specific styles. Value quantities and positions are interpreted as follows.

Number of values | Effect
--- | ---
1 | All four borders set to value
2 | Top and bottom borders set to the first value, right and left borders set to the second value
3 | Top border set to first value, right and left borders set to second value, bottom border set to third value
4 | Top, right, bottom, and left borders set, respectively

Initial Value
medium (IE and NN 6); 0 (NN 4)
Example
    h1 {border-style: ridge; border-width: 3px 5px 3px}
    div {border-style: solid double; border-width: 4px}
Applies To
All elements, but only block and replaced elements in IE 4 and 5 for Windows.
Object Model Reference
    [window.]document.getElementById("elementID").style.borderWidth