Lella Vignelli, a designer who, with her husband, Massimo Vignelli, introduced a spare, elegant style to a wide range of products and corporate brands, attracting an international clientele, died on Dec. 22 at her home in Manhattan. She was 82.

The cause was dementia, her son, Luca, said.

Ms. Vignelli, an architect by training, brought a three-dimensional imagination to her husband’s graphic-design sensibility. Together, they were a two-person design army with a shared aesthetic — sleek and intelligent — that appealed to clients eager to express a new identity or to develop products with bold, modernist lines.

After working with Italian companies like Pirelli and Olivetti in the early 1960s, the Vignellis established an American base of operations through Unimark, their corporate branding company, and, later, Vignelli Associates, which they founded in 1971, and a sister company, Vignelli Designs, which began in 1978.

The Vignellis gave American Airlines its double-A logo and Bloomingdale’s its signature brown paper bags. They designed brightly colored melamine dishware for Heller, stacking fiberglass chairs for Knoll and the interior of St. Peter’s Church — the triangular structure at the base of the building previously known as Citicorp Center in Midtown Manhattan — from the pews to the altarware to the organ.