Mislim da ti ljubičasta haljina ljepše stoji od plave haljine.

Mislim da means I think that.

In Croatian, da is very commonly used to introduce a clause after verbs like think, know, say, hope, and so on:

• Mislim da... = I think that...
• Znam da... = I know that...
• Kaže da... = He/She says that...

So the sentence structure is very natural:

• Mislim da ti ljubičasta haljina ljepše stoji od plave haljine.
• I think that the purple dress suits you better than the blue dress.

Croatian usually keeps da in places where English often drops that.

Here ti is the dative form of ti = to you.

In this sentence, it goes with stoji in the sense of looks on someone / suits someone:

• Haljina ti stoji. = The dress suits you / looks good on you.

So ti does not mean you as the subject. It means something more like:

• on you
• to you
• for you in the grammatical sense

Compare:

• Meni ta boja dobro stoji. = That color suits me well.
• Tebi crno lijepo stoji. = Black looks nice on you.

Yes, stajati literally means to stand, but it also has an extended meaning when talking about clothes, colors, hairstyles, and similar things:

• dobro stajati nekome = to suit someone / to look good on someone

So here:

• ljubičasta haljina ti stoji = the purple dress suits you / looks good on you

This is a very common Croatian way to talk about appearance. English uses a different verb, but Croatian often uses stajati in this context.

Similar examples:

• Ta ti boja dobro stoji. = That color suits you.
• Kratka kosa joj lijepo stoji. = Short hair looks nice on her.

Because ljepše here is an adverb, not an adjective.

It describes how the dress suits the person:

• lijepo stoji = looks nice / suits nicely
• ljepše stoji = looks nicer / suits better

If you used ljepša, that would be an adjective meaning more beautiful, and it would describe a noun, not the verb stoji.

So compare:

• Ljubičasta haljina je ljepša od plave.
  = The purple dress is more beautiful than the blue one.
  Here ljepša describes haljina.

• Ljubičasta haljina ljepše stoji od plave.
  = The purple dress suits you better than the blue one.
  Here ljepše describes stoji.

That is an important difference in meaning.

Ljepše is the comparative form of lijepo.

The pattern is:

• lijepo = nicely / beautifully
• ljepše = more nicely / better-looking
• najljepše = most nicely

This comes from the same family as:

• lijep = beautiful
• lijepa = beautiful (feminine)
• lijepo = beautiful (neuter) / beautifully

The stem changes a little:

• lijep → ljepši
• lijepo → ljepše

This kind of change is normal in Croatian comparatives.

Because it is the subject of the clause, so it is in the nominative case.

• haljina = dress
• ljubičasta haljina = purple dress

The adjective must agree with the noun in:

• gender
• number
• case

Since haljina is:

• feminine
• singular
• nominative

the adjective is also:

• ljubičasta

So:

• ljubičasta haljina = nominative feminine singular

Because od is used here to mean than in a comparison, and after od, the noun goes into the genitive case.

So:

• plava haljina = nominative
• od plave haljine = genitive after od

This is a common comparison pattern in Croatian:

• veći od brata = bigger than his brother
• ljepša od sestre = more beautiful than her sister
• bolje stoji od plave haljine = suits better than the blue dress

So the ending changes because of the preposition od.

Yes, absolutely.

Croatian often omits the repeated noun when it is obvious from context:

• Mislim da ti ljubičasta haljina ljepše stoji od plave.

This means the same thing as:

• Mislim da ti ljubičasta haljina ljepše stoji od plave haljine.

The shorter version is often more natural in everyday speech because repeating haljina is unnecessary if both items are dresses.

So:

• od plave haljine = full, explicit
• od plave = shorter, very natural

Because Croatian does not have articles like the and a/an.

So:

• haljina can mean a dress or the dress
• ljubičasta haljina can mean a purple dress or the purple dress

The exact meaning depends on context.

In this sentence, English naturally uses the because the speaker is probably comparing two specific dresses, but Croatian does not need a separate word for that.

Not completely. Croatian word order is more flexible than English word order, although some positions sound more natural than others.

The original sentence:

• Mislim da ti ljubičasta haljina ljepše stoji od plave haljine.

is very natural.

You may also hear:

• Mislim da ljubičasta haljina ti ljepše stoji od plave haljine.
• Mislim da ljubičasta haljina ljepše stoji ti od plave haljine.

But these alternatives may sound less natural depending on emphasis.

A very important point: short unstressed words like ti often tend to appear early in the clause. Croatian has a tendency to place these clitics in a special early position, which is why ti appears where it does.

So even though word order is flexible, ti is not placed randomly.

No, not if you want to say who the dress suits.

Without ti, the sentence would mean something incomplete like:

• I think the purple dress looks nicer than the blue dress

But it would lose the idea of on you / to you.

Compare:

• Ljubičasta haljina ti ljepše stoji od plave haljine.
  = The purple dress suits you better than the blue dress.

• Ljubičasta haljina je ljepša od plave haljine.
  = The purple dress is prettier than the blue dress.

These are different meanings.

Yes. Another common verb is pristajati:

• Mislim da ti ljubičasta haljina bolje pristaje od plave haljine.

This also means I think the purple dress suits you better than the blue dress.

Very roughly:

• dobro stajati = to look good on someone
• dobro pristajati = to suit someone

Both are common, and the difference is often small in everyday use.

The original sentence with stoji is completely natural.

Yes, it matters because Croatian nouns have grammatical gender, and haljina is feminine.

Because of that, words agreeing with it must also be feminine:

• ljubičasta haljina
• plava haljina

If the noun were masculine or neuter, the adjective forms would change.

For example:

• ljubičasti kaput = purple coat
• ljubičasto odijelo = purple suit

So in your sentence, the feminine endings -a are there because haljina is feminine.

Usually yes. Ljubičast means purple / violet.

The forms change depending on gender:

• ljubičast = masculine
• ljubičasta = feminine
• ljubičasto = neuter

Examples:

• ljubičast kaput = purple coat
• ljubičasta haljina = purple dress
• ljubičasto cvijeće = purple flowers / purple-colored flowers

So in this sentence, ljubičasta is simply the feminine form that matches haljina.

A very literal breakdown would be:

• Mislim = I think
• da = that
• ti = to you / on you
• ljubičasta haljina = the purple dress
• ljepše = more nicely
• stoji = stands / looks / suits
• od plave haljine = than the blue dress

So, very literally:

• I think that to you the purple dress stands more nicely than the blue dress.

That is not good English, but it helps show how the Croatian sentence is built. The natural English translation is:

• I think the purple dress suits you better than the blue dress.