This is the 3563rd most frequent Japanese word.
設計
Design; plan; layout.
Here, '設計' is used as a noun meaning 'design', specifically in the context of planning the structure or system of a house.
家を設計するのは建築士の仕事です。
Designing a house is the work of an architect.
In this sentence, '設計しました' is the past tense of the verb '設計する', which means 'to design' or 'to plan', showing the action of creating the app's structure.
彼女は新しいアプリを設計しました。
She designed a new app.
Here, '設計' is again a noun, referring to the conceptual and structural plan or design of the bridge, highlighted for its innovation.