His professional activity took him, from 1946 to 1948, to Mexico together with his family and Hannes Meyer, former director of the Bauhaus, where he collaborated in the national literacy campaign. He returned to Italy in 1948 in Milan where he began teaching at the “School of the Rinascita”.

He continues his graphic activity working for numerous magazines (Domus, Metron, Edilizia moderne), for some of the most important Italian publishing houses (Feltrinelli, Einaudi, Zanichelli), for many of the Italian left-wing newspapers (L’Unità, Il Contemporaneo, Vie Nuove, Rebirth, Labor movement, Historical magazine of socialism, Historical studies, Modern times, Problems of socialism, L’Erba voglio, Mondo Operaio, contemporary Italy) and for some companies (Pirelli, Olivetti).

From 1950 to 1954 he was art director at “La Rinascente” and was one of the promoters of the exhibition that will give rise to the “Compasso d’oro” award. And again in the 1950s he was a lecturer in Humanitarian law. Subsequently he teaches courses at the University of Venice, at the ISIA in Urbino and in the art institutes of Parma, Rome and Florence.

In 1963 the first “self-service warehouse” opens in Reggio Emilia and Steiner designs what will become the Coop brand. He collaborates with cultural bodies and institutions such as Rai, the Piccolo Teatro, the Milan Triennale, the Italian popular theater, Italy ’61, the Venice Biennale. He was a founding member of the Association for Industrial Design and a member of the AGI Alliance Graphique Internationale and the International Center of Typographic Arts.