The stage of Porto Leggero, a star of the waterfront dining scene in Jersey City, changes in the harbor light as its name suggests. On weekdays, the change that moves through the restaurant when finance types fill the house is electric. While the buzz of families sampling an evening out in the neighborhood is equally magnetic. Although the scene may change, the recipe remains the same: a magnificent open setting dressed in warm jewel tones, a stellar kitchen, and highly efficient service. Fully exposed behind a two-story wall of glass, the modern interior is softened with mahogany archways, tumbled brick, and richly textured upholstery. The finely appointed tables are dressed in white linen. Although waterfront restaurants are plentiful along the Gold Coast of the Hudson, few have a cuisine comparable to Porto Leggero.