What does "streamliner interior" mean?

Question

The wilaya (city hall) opposite was constructed in a neo-Moroccan-meets-art deco style, but step inside and the architecture takes an Arab-Andalusian feel where, from under the arches, local government officials’ offices overlook a central patio and fountain. Add to this a streamliner interior, monumental staircase, touches of Venetian style on the exterior and a modernist clock tower, and you have a building that is testament to the city’s innovative architectural heritage

Source: The Independent

MW defines streamliner as:

one that is streamlined; especially : a streamlined train

And defines streamlined as:

1

a : contoured to reduce resistance to motion through a fluid (such as air)

b : stripped of nonessentials : compact

c : effectively integrated : organized

2: having flowing lines

3 : brought up to date : modernized

So does streamliner interior mean an interior shaped in such a way to reduce air resistance, or does it mean the sense b, or c or maybe even 3?

Answer 1

In the 1920s, cars, bikes and trains were streamlined to make them go faster. This gave rise to a design style, part of the art deco movement called "Streamline Moderne". Many things were designed in the "streamlined" style, from buildings to toasters.

I think the writer here wants to distinguish between practical streamlined objects and the specific style of the 1920s and 1930s. A modern car is "streamlined" but it isn't in the "1930s streamliner style". Streamlined things were sometimes called "streamliners", and so the author is saying "in the style of the streamliners" rather than actually designed to cut through the air.