The font-weight CSS property sets the weight (or boldness) of the font. The weights available depend on the font-family that is currently set.
/* Keyword values */
font-weight: normal;
font-weight: bold;
/* Keyword values relative to the parent */
font-weight: lighter;
font-weight: bolder;
/* Numeric keyword values */
font-weight: 100;
font-weight: 200;
font-weight: 300;
font-weight: 400;/* normal */
font-weight: 500;
font-weight: 600;
font-weight: 700;/* bold */
font-weight: 800;
font-weight: 900;
/* Global values */
font-weight: inherit;
font-weight: initial;
font-weight: unset;Source: https://developer.mozilla.org/en-US/docs/Web/CSS/font-weight