Learn Hardcore Croatian: Koliko god je svemir velik, svaki mali korak u učenju jezika čini našu malu galaksiju još toplijom. - However big space is, every small step in learning the language makes our little galaxy even warmer.

Koliko god is a concessive expression meaning roughly “however (much)” / “no matter how (much)”.
So Koliko god je svemir velik means “However big the universe is / No matter how big the universe is.”

It introduces a dependent clause that admits something as true but contrasts it with the main clause.
Compare:

Koliko je svemir velik? – How big is the universe? (a direct question)
Koliko god je svemir velik, … – However big the universe is, … (a concessive clause, not a question)

You may also see Koliko god da je svemir velik; adding da is common and equally correct here.

2. Why is the word order je svemir velik instead of the more basic svemir je velik?

The neutral, statement-like order would be Svemir je velik – The universe is big.
In Koliko god je svemir velik, the word order is slightly flipped because:

It is part of a special structure introduced by Koliko god, and
Croatian word order is flexible and often changes for rhythm or emphasis.

You could technically say Koliko god svemir je velik, but it would sound odd. With Koliko god, the pattern Koliko god je X Y is very natural. Think of it as one fixed “package” that learners can memorize: Koliko god je + subject + adjective.

3. What case and function does svaki mali korak have in this sentence?

Svaki mali korak is in the nominative singular, masculine. It is the subject of the main clause.

svaki – every/each (masc. nom. sg.)
mali – small (masc. nom. sg.)
korak – step (masc. nom. sg.)

Together: Svaki mali korak (u učenju jezika) čini… – Every small step (in language learning) makes…

4. What is happening grammatically in u učenju jezika? Why these forms?

u učenju jezika literally means “in the learning of language” or more naturally “in learning a language”.

u – preposition, here used with the locative (for “in/within” a process, activity, place, etc.)
učenju – locative singular of učenje (learning, study) → u učenju = in (the) learning
jezika – genitive singular of jezik (language)

When a verb is turned into a noun (here učiti → učenje), its object usually stays in the same case it would have with the verb – so učiti jezik → učenje jezika (learning a language).
Thus u učenju jezika = in language learning / in the process of learning a language.

5. Why is it našu malu galaksiju, and what case is that?

Našu malu galaksiju is in the accusative singular, feminine, because it is the direct object of čini (makes).

Agreement:

našu – our (fem. acc. sg., agreeing with galaksiju)
malu – small (fem. acc. sg.)
galaksiju – galaxy (fem. acc. sg.)

In nominative (as a subject) it would be naša mala galaksija.
Here it is something being affected by the verb (what does each step make?), so it must be accusative: čini našu malu galaksiju…

6. Why is it još toplijom, not još toplija?

Još toplijom is:

the instrumental singular,
feminine,
of the comparative adjective topliji (warmer),
so toplijom corresponds to “warmer (as an instrumental)”.

With the verb činiti in the sense “to make something become X”, Croatian typically uses the instrumental for the resulting state:

Čini me sretnim. – It makes me happy. (instrumental sretnim)
Učinio si sobu ljepšom. – You made the room prettier. (instrumental ljepšom)

So here: čini našu malu galaksiju još toplijom – makes our little galaxy even warmer
→ još toplijom must be instrumental to fit this pattern, not nominative još toplija.

7. What exactly does još add in još toplijom?

Još here means “even” / “still (more)” in a comparative structure.

topla – warm
toplija – warmer
još toplija – even warmer / warmer still

So još toplijom = even warmer (in instrumental form). It intensifies the comparative: every small step makes our little galaxy “even warmer than before”.

8. Why is jezika in the genitive, and could you say učenje jeziku instead?

Jezika is the genitive singular of jezik and serves as the object of the noun učenje.

When verbs are turned into nouns, their objects usually stay in the same case they had with the verb:

učiti jezik – to learn a language (verb + accusative object)
→ učenje jezika – the learning of (a) language (noun + genitive, mirroring that object relationship)

The pattern is:

učenje matematike – learning (of) mathematics
učenje hrvatskog (jezika) – learning (of) Croatian

Učenje jeziku would be wrong in this meaning; jeziku is dative (to the language), which doesn’t fit here.

9. Could the word order in the main clause be changed? For example, is Svaki mali korak u učenju jezika našu malu galaksiju čini još toplijom correct?

Yes, Croatian allows flexible word order.
Your variant Svaki mali korak u učenju jezika našu malu galaksiju čini još toplijom is grammatically correct, but it sounds less natural and a bit heavy.

The original order:

Svaki mali korak u učenju jezika čini našu malu galaksiju još toplijom.

keeps:

subject + its phrase together (svaki mali korak u učenju jezika),
then verb (čini),
then object + complement (našu malu galaksiju još toplijom).

This is a very natural flow in Croatian. Moving našu malu galaksiju before čini is possible but adds a different rhythm and slight emphasis shift.

10. What is the nuance of svaki in svaki mali korak? Is it like “any” or “every”?

Svaki mainly corresponds to “every / each”.

svaki mali korak – every little step / each small step

It emphasizes that all such steps, without exception, have this positive effect.
It is not the same as bilo koji (“any (at all)”), which is more indefinite or choice-like:

bilo koji korak – any step (whichever)
svaki korak – every step (all of them, one by one)

11. Is svemir the only word for “universe”? Could you say univerzum instead?

You can use both:

svemir – the more common, everyday word for “universe”.
univerzum – also correct; sounds a bit more technical or learned, but is widely understood.

In this poetic, metaphorical sentence, svemir feels more natural and “Croatian-sounding”.
Koliko god je univerzum velik would still be grammatically fine, just stylistically slightly different.

12. Is the whole sentence neutral, or is it more poetic / figurative?

The sentence is quite figurative and warm in tone:

svemir and mala galaksija are used metaphorically,
toplija (warmer) refers not to physical temperature but to emotional warmth, friendliness, coziness.

It would fit well in motivational messages, language-learning blogs, social media posts, or speeches encouraging learners.
Grammatically it is standard and correct; stylistically, it is deliberately poetic rather than purely neutral or technical.