How to edit the buttons to pick and book a slot in the Sesami app ?

[AgatheLecocq]

Hi everybody, 

I would like to change the two green

buttons in black on this page https://mindology.fr/products/seance-decouverte-accompagnement-gestion-stress-emotions-anxiete 

The sesami app team (app for booking a slot) is saying to override the CSS class: sesami__button

Could you please assist me on where to update the color and where to find the CSS class of this buttons ? 

Thanks for your help, 

All my best,

Agathe et Léa