Standard fonts

[Monello]

Hello everyone!
Sorry if this questions doesnt belong to the right category.
I'm just curious about how do I use standard font such as 'font-family: sans-serif;'
I been successfully added and uploaded my own for the main title and certain use.
But for a standard font such as css, sans-serif I have no idea

Have a lovely holiday everyone

best wishes,
Oscar

[Hayo Gebauer]

I think choosing Helvetica form the list of existing fonts equals "sans-serif". Windows will display Arial instead

[Monello]

Thank you Hayo! :)