Koliko god je svemir velik, svaki mali korak u učenju jezika čini našu malu galaksiju još toplijom.

Here koliko god means no matter how or however.

So:

Koliko god je svemir velik
= No matter how big the universe is

It introduces a concessive clause: the first part admits something large or impressive, but the main point comes in the second part.

Croatian has no articles, so there is no separate word for the or a/an.

That means:

• svemir can mean the universe
• jezika can mean of language / of the language / of languages, depending on context
• našu malu galaksiju means our little galaxy, and our already makes it definite

English learners often look for articles, but in Croatian definiteness is usually understood from context, word order, or words like ovaj, taj, naš, etc.

Because velik is the normal form of the adjective when it is used predicatively, that is, after to be:

• Svemir je velik. = The universe is big.

In this position, Croatian usually prefers the short adjective form.

By contrast, when the adjective stands directly before a noun, you often get:

• veliki svemir = a big universe / the big universe (depending on context)

So in this sentence, velik is exactly what you would expect after je.

Yes, svemir je velik is also possible.

Croatian word order is much more flexible than English word order. In subordinate clauses like this one, the verb often appears early:

• Koliko god je svemir velik...

This sounds natural and slightly literary or rhetorical. Other orders are possible too, with small changes in emphasis:

• Koliko god je velik svemir...
• Koliko god svemir bio velik...

The version in your sentence is not about changing the basic meaning; it is mainly about style and emphasis.

Svemir is in the nominative singular because it is the subject of je in the clause:

• svemir = subject
• je velik = predicate

So the structure is basically:

• Svemir je velik. = The universe is big.

Svaki mali korak is also in the nominative singular because it is the subject of the main verb čini.

Breakdown:

• svaki = masculine singular nominative
• mali = masculine singular nominative
• korak = masculine singular nominative

They all agree with each other because they belong to the same noun phrase:

svaki mali korak = every small step

This phrase means in language learning or in the learning of a language.

Grammar:

• u
  • locative is used here
• učenju is the locative singular of učenje = learning
• jezika depends on učenje

So:

• u učenju = in learning
• u učenju jezika = in language learning

This is a very common Croatian structure.

Jezika is genitive.

The noun učenje comes from the verb učiti. When a Croatian verb is turned into a noun, the thing being learned often appears in the genitive:

• učiti jezik = to learn a language
• učenje jezika = learning of a language / language learning

One extra detail: jezika can be genitive singular or genitive plural in form. So without wider context, it can mean:

• of a language
• of languages

In this sentence, it is most naturally understood in a general sense: language learning.

Here čini comes from činiti, which can mean to make, to render, or to cause to become.

The pattern is:

činiti + accusative object + instrumental complement

So in your sentence:

• našu malu galaksiju = the thing being affected, in the accusative
• još toplijom = what it is being made, in the instrumental

A simpler example:

• To ga čini sretnim. = That makes him happy.

So the structure is very similar in your sentence.

Because they have different grammatical roles.

1. našu malu galaksiju

This is the direct object of čini, so it is in the accusative singular:

• našu = feminine singular accusative
• malu = feminine singular accusative
• galaksiju = feminine singular accusative

2. još toplijom

This is the resulting state after čini, so it is in the instrumental singular:

• toplijom = feminine singular instrumental of toplija / comparative base topliji

It agrees with galaksiju in gender and number, but not in case, because it is not another object. It is a complement meaning warmer.

So:

• čini našu malu galaksiju još toplijom = makes our little galaxy even warmer

Here još means even or still in the sense of even more.

So:

• toplijom = warmer
• još toplijom = even warmer

It strengthens the comparison. The sentence is saying that each small step does not just make the galaxy warm, but warmer than before.

It is clearly poetic/metaphorical.

Expressions like:

• naša mala galaksija
• još toplijom

are not meant as literal astronomy. They create an image of a small shared world, community, or emotional space becoming friendlier and warmer through language learning.

So a learner should understand that the grammar is normal, but the style is figurative and expressive.