Learn Hardcore Croatian: Kapetanica se smiješi publici kako bi zadržala opušteno raspoloženje u dvorani. - The captain smiles at the audience in order to keep a relaxed mood in the hall.

Croatian often has separate feminine forms for professions and roles (učitelj / učiteljica, glumac / glumica, etc.). Here the subject is a woman, so kapetanica is used.

What is the function of se in kapetanica se smiješi?

Se is a reflexive pronoun, and in this verb it’s part of the dictionary form: smiješiti se = to smile.

You generally cannot drop se here; smiješiti without se isn’t used with the meaning to smile. So you should treat smiješiti se as a unit, similar to how English has phrasal verbs.

What is the difference between smiješi se and smije se?

They come from two different verbs:

smiješiti se → smiješi se = she smiles (a gentle, continuous smiling)
smijati se → smije se = she laughs (or is laughing)

So:

Kapetanica se smiješi publici. = The captain is smiling at the audience.
Kapetanica se smije publici. = The captain is laughing at the audience. (can sound like making fun of them, depending on context)

In your sentence, smiješi se is chosen to suggest a friendly, calming smile.

Why is it publici and not publiku? Which case is this?

Publici is the dative singular of publika (audience).

In Croatian, with verbs of communication or directed action (smile to someone, speak to someone, write to someone), the person you direct the action to is often in the dative:

smiješiti se publici – to smile to/at the audience
govoriti publici – to speak to the audience

Publiku would be accusative, used if the audience were a direct object in some other type of action (e.g. vidim publiku – I see the audience).

Could we say smiješi se na publiku instead of smiješi se publici?

You might occasionally hear smiješi se na publiku, but:

The most natural and standard way is smiješi se publici (dative without a preposition).
na with the accusative (na publiku) can sound more literal/physical, like pointing your smile onto them as an object, and may feel less idiomatic.

For everyday, neutral speech, stick with smiješi se publici.

What does kako bi zadržala mean, and why is bi used here?

Kako bi zadržala literally means “so that she would keep / in order to maintain”.

kako here = “so that / in order that”
bi is the auxiliary for the conditional mood
zadržala is the (feminine) past participle used with bi to form the conditional

So kako bi zadržala expresses purpose, very close to English so that she keeps / to keep, but with a slight nuance of intention or potential action: so that she would keep (it).

What is the difference between kako bi zadržala and da zadrži?

Both express purpose, but there are small stylistic and grammatical differences:

kako bi zadržala opušteno raspoloženje
- conditional (bi + zadržala)
- slightly more formal/literary
- often used in written style, explanations, descriptions
da zadrži opušteno raspoloženje
- present tense (zadrži) in a da-clause
- very common in everyday speech
- neutral style

In most contexts, you could replace kako bi zadržala with da zadrži without changing the basic meaning.

Why is zadržala in the feminine form?

In the conditional, the past participle agrees with the subject in gender and number.

Subject: kapetanica → feminine singular
Conditional: (ona) bi zadržala = she would keep

If the subject were masculine singular (kapetan), it would be:

(on) bi zadržao opušteno raspoloženje

So the -la ending marks feminine singular agreement.

What is the difference between zadržati and zadržavati? Why zadržala here?

They differ in aspect:

zadržati (perfective) – to keep, to retain (a completed or targeted action)
- zadržala = she (would) keep / would have kept
zadržavati (imperfective) – to be keeping, to keep repeatedly or continuously
- zadržavala bi = she would be keeping / would keep (over time)

In purpose clauses like this, the perfective is very common, because it focuses on successfully achieving the goal: kako bi zadržala opušteno raspoloženje = so that she (successfully) keeps the relaxed mood.

Why is it opušteno raspoloženje and not opuštena raspoloženje?

Raspoloženje (mood) is neuter singular.
Adjectives must agree in gender, number, and case with the noun they modify:

neuter singular nominative: opušteno raspoloženje
masculine singular: opušten (e.g. opušten čovjek)
feminine singular: opuštena (e.g. opuštena osoba)

So opušteno is the correct neuter form to match raspoloženje.

Could we say opuštenu atmosferu instead of opušteno raspoloženje?

Yes, but there’s a subtle nuance:

opušteno raspoloženje – literally relaxed mood; focuses a bit more on how people feel emotionally.
opuštena atmosfera – relaxed atmosphere; focuses a bit more on the overall feel or vibe of the room.

Both are natural and often interchangeable in this context. The grammar would then change accordingly (e.g. kako bi zadržala opuštenu atmosferu u dvorani – accusative feminine -u).

Why is it u dvorani and not u dvoranu? Which case is that?

U dvorani uses the locative case (dvorana → dvorani) after u to indicate location:

u
- locative → being in a place (static)
  - u dvorani = in the hall
u
- accusative → movement into a place
  - u dvoranu = into the hall

Here we’re talking about the mood in the hall (not moving into it), so u dvorani is correct.

What exactly does dvorana mean, and how is it different from soba or prostorija?

dvorana – a hall, usually large, often for events: sports hall, concert hall, lecture hall.
soba – a room (bedroom, living room, etc., usually in a home or smaller setting).
prostorija – a more general word for a room/space inside a building, often technical or neutral.

In this sentence, u dvorani suggests a bigger public space (auditorium, hall) with an audience.

Is the word order Kapetanica se smiješi publici fixed, or can it change?

The word order is relatively flexible, but se (a clitic) must stay near the verb. All of these are possible, with slight emphasis differences:

Kapetanica se smiješi publici. (neutral, standard)
Kapetanica publici se smiješi. (less common; emphasis shifts)
Publici se kapetanica smiješi. (emphasis on publici, “it’s the audience she’s smiling at”)

What you generally cannot do is move se far away from the verb or leave it out.