Learn Hardcore Croatian: Naš projekt je velik, pa često ostajemo u uredu do kasno. - Our project is big, so we often stay in the office until late.

In predicative position (after the verb biti “to be”), Croatian often prefers the short form of the adjective: projekt je velik. Before a noun (attributive), you typically use the long form: veliki projekt. In modern usage, many speakers also say projekt je veliki; it’s widely heard and not wrong, but careful/neutral standard style favors velik in this spot.

What exactly does pa mean here, and how is it different from zato, jer, or tako da?

pa: a mild, often colloquial coordinator meaning “so/and so/and then,” signaling a loose cause/result or sequence.
zato: “therefore/so,” a clearer consequence marker. Example: …, zato često ostajemo…
jer: “because,” introduces a reason clause. Using it here would flip the logic: Naš projekt je velik jer često ostajemo… = “Our project is big because we stay late,” which isn’t the intended meaning.
tako da: “so that/as a result,” introduces a result clause: …, tako da često ostajemo… = “…, so (as a result) we often stay…”

Is the comma before pa necessary?

It’s not required by strict prescriptive rules (you generally don’t need a comma before the coordinating pa), but many writers do include it to mark a pause. Both versions are common:

Without comma (more by-the-book): Naš projekt je velik pa često ostajemo…
With comma (very common in practice): Naš projekt je velik, pa često ostajemo…

Why is it u uredu and not u ured?

With static location, u takes the locative case: u uredu (“in the office”). If it were motion into, you’d use the accusative: u ured (“into the office”).
Minimal forms of ured (m.) for reference:

N sg: ured; G sg: ureda; L sg: uredu; A sg: ured

Can I say u kancelariji or na poslu instead of u uredu?

u uredu = “in the office” (standard Croatian).
u kancelariji is more typical for Serbian/Bosnian; it’s understood but not the default in Croatian.
na poslu = “at work” (broader than just “in the office”), and is very common and natural.

Could često go somewhere else? For example, Često ostajemo… or Ostajemo često…?

Yes. Common and natural placements:

Često ostajemo u uredu do kasno. (fronted frequency = common)
Naš projekt je velik, često ostajemo u uredu do kasno. (new sentence/clause)
Ostajemo često u uredu do kasno. (also possible; end-placed adverb can add a slight emphasis)
Croatian word order is flexible; keep adverbs near the verb for clarity.

Why ostajemo and not ostanemo? What’s the aspect difference?

ostajemo is the present of the imperfective ostajati and fits habitual actions: “we often stay.”
ostanemo is the present of the perfective ostati; perfective “present” usually refers to future-like or conditional contexts, e.g., Ako ostanemo do kasno… (“If we stay late…”). For a one‑off future plan, use the future: ostat ćemo.

Could I say radimo do kasno instead of ostajemo do kasno?

Yes, but there’s a nuance:

ostajemo do kasno highlights remaining in the office (staying late at the workplace).
radimo do kasno highlights the activity (working late), regardless of location.
Both are natural; choose based on what you want to emphasize.

Why do kasno? Is do kasna also correct? What about other variants?

do kasno (“until late”) is standard and very common.
do kasna is also widely used colloquially and accepted; some hear it as slightly more informal/regional.
You can expand for nuance: do kasno u noć, do kasnih sati, do kasno navečer.

Can I drop do and just say ostajemo kasno?

Avoid that. The idiomatic way to express “stay late” is ostajemo do kasno. Without do, ostajemo kasno sounds off or ambiguous. Alternatives include radimo do kasno or ostajemo dugo (“we stay for a long time”).

Could I reorder it as Naš je projekt velik?

Yes. The clitic je wants the “second position” in the clause. In:

Naš projekt je velik, the first prosodic unit is Naš projekt, so je comes after it.
Naš je projekt velik, the first word is Naš, so je comes right after it.
Both are correct and natural.

Why projekt and not projekat?

In standard Croatian it’s projekt. projekat is the standard Serbian form. Croatian readers will understand projekat, but in Croatia you should write projekt.

How does do work with time expressions in general?

do means “until/up to” and typically governs the genitive with nouns:

do ponoći (until midnight), do sutra (until tomorrow), do pet sati (until 5 o’clock), do jutra (until morning).
With adverbs like kasno, you’ll see the fixed adverbial do kasno.

Is u uredu do kasno the best order, or can I say do kasno u uredu?

Both are possible. The typical, neutral rhythm places place before time:

(… ) ostajemo u uredu do kasno.
Putting do kasno late in the sentence is also natural in Croatian; just keep the chunks together and the meaning clear.

Could I replace pa with something else to sound a bit more formal?

Yes:

…, zato često ostajemo u uredu do kasno. (therefore)
…, tako da često ostajemo u uredu do kasno. (so/as a result)
Both are a touch more explicit/formal than pa.