По мере того как кофе готовился в кофеварке, на кухне становилось уютнее.

It means as, while, or more literally in proportion as. It shows that one process develops gradually at the same time as another.

So in this sentence:

• По мере того как кофе готовился в кофеварке...
• As the coffee was brewing in the coffee maker...

It is not just saying that two things happened at once. It suggests a gradual parallel change: the more the coffee progressed toward being ready, the cozier the kitchen felt.

Because по мере того как adds the idea of gradual development.

Compare:

• когда = when
• пока = while
• по мере того как = as / as more and more / in step with

So:

• Когда кофе готовился... = When the coffee was being made...
• Пока кофе готовился... = While the coffee was being made...
• По мере того как кофе готовился... = As the coffee was brewing, little by little...

This sentence is about atmosphere slowly changing, so по мере того как is especially natural.

Because кофе is traditionally masculine in standard Russian.

So in the past tense, the verb agrees like this:

• masculine: готовился
• feminine: готовилась
• neuter: готовилось
• plural: готовились

Since кофе is masculine, we get кофе готовился.

This surprises English speakers because кофе ends in -е, which often looks neuter, but кофе is an exception.

Here готовился comes from готовиться, and it has a kind of middle/passive-like meaning: was being prepared / was getting made.

So:

• готовить кофе = to make/prepare coffee
• кофе готовился = the coffee was being prepared / the coffee was brewing

The -ся does not mean the coffee is literally doing something to itself. In many Russian verbs, -ся can make the action feel less focused on the person doing it and more on the process itself.

That is why this sounds natural in a sentence describing atmosphere and background action.

Yes, you might hear варился, but it gives a slightly different feel.

• готовился = was being prepared / was getting made
• варился = was boiling / was being brewed

With coffee, готовился is broader and fits well with a coffee maker.
Варился can sound more specific to the brewing process itself, and sometimes more like traditional preparation rather than just machine-made coffee.

So готовился в кофеварке is very natural here.

В кофеварке is prepositional case after в, because it expresses location: in the coffee maker.

• в кофеварке = in the coffee maker where the coffee is being prepared

If в expresses motion into something, it usually takes the accusative.
If it expresses location, it usually takes the prepositional.

Here there is no movement into the coffee maker, only location, so в кофеварке is correct.

Because на кухне is the normal idiomatic way to say in the kitchen / in the kitchen area in Russian.

Even though English uses in, Russian often uses на with certain places, especially when thinking of them as functional spaces or areas:

• на кухне = in the kitchen
• на работе = at work
• на почте = at the post office

В кухне is not impossible, but it sounds unusual in everyday speech and may feel more architectural or literal, as if you are emphasizing the physical interior of the room.

So for normal conversation, на кухне is the form learners should expect.

This part is an impersonal construction.

Literally, на кухне становилось уютнее means something like:

• it was becoming cozier in the kitchen

There is no explicit grammatical subject, so Russian often uses the past tense in the neuter singular:

• становилось

If you named a subject, then the verb would agree with it:

• Кухня становилась уютнее. = The kitchen was becoming cozier.

But in the original sentence, Russian is not saying that the kitchen as a noun is the subject. It is describing a general change of atmosphere in that location.

Уютнее is the comparative form of уютный / уютно and means cozier / more cozy.

In this sentence it works like a predicative comparative:

• становилось уютнее = was becoming cozier

Russian often prefers the simple comparative form:

• уютнее = cozier
• теплее = warmer
• тише = quieter

Instead of using более + adjective/adverb, Russian very often just uses this one-word comparative.

Because the sentence describes ongoing, gradual processes in the past, not completed one-time events.

• готовился = the coffee was in the process of being made
• становилось = it was gradually becoming cozier

This matches the meaning of по мере того как, which naturally goes with actions unfolding over time.

If you used perfective forms, the sense of gradual parallel development would be much weaker or unnatural.

Because По мере того как кофе готовился в кофеварке is a subordinate clause, and it is separated from the main clause by a comma.

Structure:

• subordinate clause: По мере того как кофе готовился в кофеварке
• main clause: на кухне становилось уютнее

Russian normally puts a comma between these parts, just as English would separate a similar dependent clause.

Yes. Russian word order is flexible, and you could say:

• На кухне становилось уютнее, по мере того как кофе готовился в кофеварке.

That is grammatically correct.

But the original order is very natural because it first introduces the background process—the coffee brewing—and then gives the resulting atmosphere. It feels smooth and literary:

• first: the coffee is brewing
• then: the kitchen feels cozier

So the original version is probably the most elegant choice for this context.

Mostly it means the atmosphere in the kitchen was becoming cozier.

Russian often uses this kind of impersonal phrasing to describe how a place feels, not necessarily a physical change in the room itself.

So the idea is not that the kitchen was literally transformed. It is that, as the coffee brewed, the kitchen felt warmer, nicer, more inviting.