Examples of websites using
Avenir
(Avenir is a sans-serif font designed by Adrian Frutiger and Nadine Chahine, released by Linotype in 1988. It features clean and modern letterforms and is available in multiple weights and styles)
with
Open Sans
(Open Sans is a sans-serif font designed by Steve Matteson. It offers a wide range of styles, including regular, italic, bold, bold italic, and light)