Examples of websites using
Plain
('Plain' is a sans-serif font designed by François Rappo and released by Optimo in 2013. The family consists of 11 individual styles, including regular, italic, and bold weights)
with
Stratos
(designed by Emmanuel Labard, Yoann Minet, Ilya Ruderman, Irene Vlachou and Yury Ostromentsky and released by Production Type in 2016)