Premda još nisam kupila čestitku, već znam što ću u njoj napisati.

Premda means although, even though, or though.

It introduces a contrast:

• Premda još nisam kupila čestitku... = Although I haven’t bought a card yet...

It is perfectly correct and standard Croatian. A very common alternative is iako, which means almost the same thing:

• Iako još nisam kupila čestitku...

Many learners hear iako more often in everyday speech, while premda can sound a little more formal or literary, but it is still very normal.

The comma separates the subordinate clause from the main clause.

Structure:

• Premda još nisam kupila čestitku = subordinate clause
• već znam što ću u njoj napisati = main clause

Croatian uses commas with subordinate clauses more regularly than English does, so this comma is expected.

They create a very natural contrast:

• još nisam kupila = I haven’t bought (it) yet
• već znam = I already know

So the sentence balances two ideas:

• one thing has not happened yet
• another thing is already decided

This is very idiomatic in Croatian:

• još ne... = not yet
• već... = already

Because Croatian is talking about whether the action of buying has happened up to now.

Nisam kupila is the perfect tense:

• nisam = I have not
• kupila = past participle-like form agreeing with the speaker

English uses haven’t bought, and Croatian usually uses the perfect here:

• Nisam kupila = I haven’t bought

A present-tense form like ne kupujem would mean I am not buying or I don’t buy, which is a different idea.

Yes.

In Croatian, the past form agrees with the gender of the speaker:

• kupila = female speaker
• kupio = male speaker

So:

• još nisam kupila čestitku = said by a woman
• još nisam kupio čestitku = said by a man

This is one of the first things English speakers notice, because English past tense does not show the speaker’s gender.

Because čestitku is the accusative singular, and it is the direct object of kupiti (to buy).

• dictionary form: čestitka
• object form: čestitku

Compare:

• Čestitka je lijepa. = The card is nice.
  Here it is the subject, so nominative: čestitka
• Kupila sam čestitku. = I bought a card.
  Here it is the object, so accusative: čestitku

Here čestitka means a greeting card.

Depending on context, it could be:

• a birthday card
• a holiday card
• a congratulatory card
• another kind of written card with a message inside

In this sentence, because the speaker says što ću u njoj napisati (what I’ll write in it), it clearly means a physical card you can write in.

Njoj here is the locative singular form of ona (she/it), and it refers back to čestitku.

Since čestitka is a feminine noun, the pronoun must also be feminine:

• čestitka → u njoj = in it

So:

• u njoj literally means in her, but in normal English we translate it as in it, because it refers to the card.

Because Croatian distinguishes between:

• location: where something happens
• direction/movement: where something goes

With u:

• u + accusative = into, movement toward the inside
• u + locative = in, inside, location

Here the meaning is write in the card, so it is a location, not movement:

• u njoj napisati = write in it

If you said u nju, that would suggest movement into it, which is not the intended idea here.

This means what I will write.

Breakdown:

• što = what
• ću = I will
• napisati = write / more exactly write down, complete the writing of

So:

• što ću napisati = what I will write

This is a subordinate clause after znam:

• znam što ću napisati = I know what I’ll write

Because ću is a clitic, and Croatian clitics usually go in second position in their clause.

In the clause:

• što ću u njoj napisati

the first element is što, so the clitic ću comes right after it.

This second-position behavior is very common in Croatian:

• Znam da ću doći.
• Ne znam što ću reći.
• Rekla je da će doći.

For an English speaker, this may feel unusual at first, but it is a core feature of Croatian word order.

Because napisati is perfective, and pisati is imperfective.

Here the speaker means a complete action:

• deciding the message that will end up written in the card

So napisati is natural:

• što ću napisati = what I’ll write / what I’m going to write down

If you used pisati, it would focus more on the process of writing rather than the completed result, so it sounds less natural in this context.

This is a common Croatian aspect contrast:

• pisati = to be writing, to write in general
• napisati = to write something and finish it

Some parts can move, but not completely freely.

The given sentence is natural and neutral:

• Premda još nisam kupila čestitku, već znam što ću u njoj napisati.

You could also hear slight variations, for example:

• Premda još nisam kupila čestitku, već znam što ću napisati u njoj.

That still works, but it shifts the focus a little.

What is less flexible is the placement of clitics like ću and forms like nisam, which follow Croatian clitic rules.

So the short answer is:

• yes, Croatian word order is flexible
• but no, it is not random

In many spoken varieties, yes, people often say šta in everyday speech.

So you may hear:

• već znam šta ću u njoj napisati

But in standard written Croatian, što is usually preferred here.

For a learner, it is best to recognize both:

• što = more standard/written
• šta = very common in speech in many regions

Not with exactly the same meaning.

• ali means but
• već here means already

So:

• već znam = I already know

If you said:

• Premda još nisam kupila čestitku, ali znam...

that would sound unnatural in standard Croatian, because premda already introduces the contrast. After that, the main clause does not need ali.

So in this sentence, već is not a conjunction like but. It is an adverb meaning already.