Twenty-six square metres in Posillipo, Naples. A forgotten flat that served no purpose for years. The architect Paola Sola turned it into what she describes as a home with a slow rhythm and Mediterranean features - and what changed the maths most is not the walls, but the fifty-square-metre courtyard with lemon trees, which practically doubles the usable area.

Not just any blue and any yellow would do

The base is neutral - that is what keeps twenty-six square metres from closing in. On top of it sit two colours: an intense blue and a light yellow. The blue comes from the colour of the fishing boats on that coast and from the region's traditional joinery. The yellow comes from the lemons growing outside, a few metres from the door.

Paola stresses these were not arbitrary choices. When the palette is reduced to two colours, the exact shade decides everything - the same blue in a different tone would make the flat cold rather than Mediterranean. That is the difference between design and guessing by taste.

From lines to curves

The graphic language is the second tool. Stripes on the bedding, a zigzag pattern in the kitchen and the bathroom, arched openings instead of straight doors. The ceramics are from Archea - a local tradition that ties the interior to the area. The repeated geometric motifs create continuity between rooms that are physically separated by a few steps.

A hallway that does three things at once

The small distributor between the public and private parts is not wasted space. Arched openings mark the transition without building a wall. A fitted wardrobe solves clothes storage, and mirrored panels camouflage the technical infrastructure - the thing most flats hide behind a door nobody ever opens properly.

The bathroom: a raised platform and one iron bar

Compact, but with character. The shower platform optimises the area and leaves comfortable movement. The ceramics are white and blue with a geometric pattern, and the yellow pendant lights from Creative-Cables bring back the base palette. The central move is a handmade enamelled iron bar holding two round mirrors, baskets and hooks - and it is a decorative element at the same time. The rectangular basin collides with the round mirrors, and the ceiling is softened by a transition that breaks the rectangularity without cluttering the space. A small window to the courtyard provides ventilation.

One room, four functions

The main space is deliberately pared back: kitchen, sitting, dining and sleeping in one. A folding table from Zara Home with two wooden chairs works as both a dining table and a workspace. The sofa from Maisons du Monde is daytime rest and, when needed, a bed. This is what architects call multifunctionality, and anyone who has lived in a studio knows it by another name: nothing in the room may have only one purpose.

The bedroom that lives off a single roof window

The back of the flat has three blind walls. The only light comes from one roof window, and the bed is placed directly beneath it. The fabric above it softens the light and creates a sense of shelter. The furniture is iron in lemon yellow - open shelves, mirrors, hooks and built-in lights in one light structure that solves storage without taking up volume.

The kitchen that does not enter the room

The kitchen is an open corner by the entrance - minimal but fully equipped, and deliberately not entering the main room. The lower units are blue, the upper ones an intense lemon yellow. The blue wall continues behind them, and above the worktop is a ceramic splashback with a yellow and white zigzag pattern. This is where most of the whole flat's graphic energy gathers in one place.

The courtyard among the lemons

The fifty square metres outside are the real room. The interwoven lemon trees make a natural roof with broken shade, and the scent is part of entering the flat. Three pots on stands greet the visitor at the door. The view runs towards the Bay of Naples with Vesuvius behind it - and that view is the source of every colour decision inside.

What of this applies here

Not many people have Vesuvius on the horizon. But the logic transfers to any balcony: take the colour from what you see through the window rather than from a catalogue; make every piece of furniture carry more than one function; and treat the outdoor part as a room, not as storage for a fridge, boxes and things waiting to be thrown out. That is not a question of budget. It is a question of what we count as part of the flat.