css issue with Skirmish WP theme

I use the Skirmish theme (slightly customised) and I have an issue with my style

My CSS used to state

strong, b {
font-weight: 900;

}

I changed it to

strong, b {
font-weight: bold;

}

as per the instructions spotted on this forum.

A test post is available at
https://visionarymarketing.fr/blog/2015/04/la-transformation-digitale-des-societes-de-taxis-est-en-marche/

And the test bold-type face sentence is
“on peut s’interroger sur la capacité de l’économie traditionnelle à évoluer pour tirer parti de la technologie face aux entreprises ? digital natives ?.”
In the top paragraph.