If you want to control the weight of your font ( its thickness ), using font weight is the best way to go about it. We suggest that you only use font-weight in multiples of 100 (e.g. 200, 300, etc) because any less and you probably will not see any difference. The values range from 100(thin)-900(thick).
normal: Defines normal characters
bold: Defines thick characters
bolder: Defines thicker characters
lighter: Defines lighter characters
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