Check out example codes for "css bold weight". It will help you in understanding the concepts better.

Code Example 1

/* key word "lighter", "normal", "bold", or "bolder" */ 
.normal {
  font-weight: normal;
}

/* number between 100 and 900 */
.heavy {
  font-weight: 900;
}

Code Example 2

font-weight: bold;

Code Example 3

/* key word "lighter", "normal", "bold", or "bolder" */ 
.normal {
  font-weight: normal;
}

/* number between 100 and 900 */
.heavy {
  font-weight: 900;
}

Code Example 4

font-weight: 200; /*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*/

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