100, 200, 300, 400, 500, 600, 700, 800, 900 Defines from thin to thick characters. 400 is the same as normal, and 700 is the same as bold. In earlier versions of the font-weight specification, the property accepts only keyword values and the numeric values 100, 200, 300, 400, 500, 600, 700, 800, and 900; non-variable fonts can only really make use of these set values, although fine-grained values (e.g. 451) will be translated to one of these values for non-variable fonts using the Fallback weights system