font-weight | NN 4 IE 4 CSS 1
| Inherited: Yes
Sets the weight (boldness) of the element's font. CSS provides a weight rating scheme that is more granular than most browsers render on the screen, but the finely tuned weights may come into play when the content is sent to a printer. The scale is a numeric rating from 100 to 900 at 100-unit increments. Therefore, a font-weight of 100 is the least bold that can be displayed, whereas 900 is the boldest. A setting of normal (the default weight for any font) is equivalent to a font-weight value of 400; the standard bold setting is equivalent to 700. Other settings (bolder and lighter) let you specify a weight relative to the parent element's weight.

The CSS2 specification offers guidelines about how the weight values should correspond to font family names and internal characteristics of some font definition formats. For example, the OpenType font definition format provides slots for nine font weights. In this case, the numeric font-weight attribute values map directly to the weight definitions in that font. If the font family contains a face with a name that contains the word Medium and one labeled Book, Regular, Roman, or Normal, the Medium face is equated with a weight value of 500 (whereas the other is at 400). All font face names including the word Bold are equated with a weight of 700. For font families that don't have all nine weights assigned, the browser should do its best to interpolate, but it is very likely that some weight values generate fonts of the same weight as other values.

CSS Syntax
    font-weight: fontWeight
Value
Any of the following constant values: bold | bolder | lighter | normal | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900.
Initial Value
normal
Example
    p em {font-weight: bolder}
Applies To
All elements.
Object Model Reference
    [window.]document.getElementById("elementID").style.fontWeight