The GRASS GIS logo text is using the Fira Sans open font family. 'GRASS' is written with FiraSans Medium and 'GIS' with the FiraSans Thin typeface.
These are the three main colors used for the GRASS GIS logo. The GRASS weed is green, frame and text are black. Monochrome version of the logo is also allowed.
This website is using the GRASS GIS web theme for Hugo, which extends the GRASS GIS brand for web and mobile.