You could use font-weight. It is explained here: https://www.w3schools.com/cssref/pr_font_weight.asp
I hope that helps.
i think Roeland will be very happy with you guys answering this question... keep up the good work :D
I think everyone who will find this question in his favorit search engine, will be happy that there is an answer for the question, anyway how long the difference is between the question and the answer.
unanswered question from 8 years ago....strange:P