Mislim da ti narančasta kapa lijepo stoji, a ljubičasta haljina još ljepše.

Yes—literally, stajati means to stand. But with clothes, colors, hairstyles, and similar things, dobro/lijepo stajati nekome means to suit someone or to look good on someone.

So:

• Kapa ti lijepo stoji. = The cap looks nice on you / suits you.
• Plava boja ti dobro stoji. = Blue suits you.

This is a very common Croatian way to talk about appearance.

Here ti is the dative form of you (singular, informal).

The verb pattern is:

• nešto stoji nekome = something suits someone

So in this sentence:

• narančasta kapa = the thing that suits
• ti = the person it suits

That is why Croatian uses the dative.

Tebi is also dative, but it is the full/stressed form, while ti is the short/clitic form.

• Kapa ti lijepo stoji. = normal, neutral
• Kapa tebi lijepo stoji. = more emphatic, like The cap looks good on you (maybe not on someone else)

Tebe would be the wrong case here.

Because lijepo here is an adverb, not an adjective.

It describes how the cap suits you:

• lijepo stoji = looks nice / suits nicely

Adverbs in Croatian often end in -o:

• dobro
• lijepo
• loše
• brzo

If it were an adjective describing a noun, then it would have to agree with that noun:

• lijepa kapa = a pretty cap

But here we are not saying the cap itself is pretty; we are saying it looks good on you.

They are adjectives agreeing with feminine singular nouns in the nominative:

• narančasta kapa = orange cap
• ljubičasta haljina = purple dress

Both kapa and haljina are feminine singular nouns, so the adjectives also take the feminine singular nominative ending -a.

That is standard adjective agreement in Croatian:

• masculine: e.g. crni kaput
• feminine: e.g. crna haljina
• neuter: e.g. crno odijelo

Here:

• narančasta matches kapa
• ljubičasta matches haljina

The verb is understood and omitted because it would repeat information from the first clause.

Full version:

• Mislim da ti narančasta kapa lijepo stoji, a ljubičasta haljina ti stoji još ljepše.

In natural Croatian, repeating ti stoji is often unnecessary, so speakers leave it out:

• ...a ljubičasta haljina još ljepše.

This kind of omission is very common when the missing words are obvious from context.

Here još ljepše means even more nicely, or more naturally in English, even better.

• lijepo = nicely / well
• ljepše = more nicely / better
• još ljepše = even more nicely / even better

So the comparison is:

• the orange cap suits you nicely
• the purple dress suits you even better

In Croatian, još often strengthens a comparative:

• još bolje = even better
• još gore = even worse
• još brže = even faster

Here a is a contrastive connector. Depending on context, it can be translated as and, while, or but.

In this sentence it connects two ideas and adds a comparison:

• the orange cap suits you nicely
• the purple dress suits you even better

So a here is something like:

• and
• while
• but

A natural English translation might be:

• I think the orange cap suits you nicely, and the purple dress even more.

or

• I think the orange cap looks nice on you, but the purple dress looks even better.

So a often signals a mild contrast, not a strong contradiction.

Mislim da... means I think that...

Croatian normally uses da to introduce a subordinate clause after verbs like:

• mislim = I think
• znam = I know
• vidim = I see
• kažem = I say

So:

• Mislim da ti kapa lijepo stoji. = I think the cap suits you.

This is a very common structure in Croatian.

English often drops that:

• I think (that) the cap suits you.

Croatian usually keeps da.

The sentence has a natural Croatian word order, but Croatian word order is fairly flexible.

Current version:

• Mislim da ti narančasta kapa lijepo stoji...

A rough structure is:

• Mislim = I think
• da = that
• ti = to you
• narančasta kapa = orange cap
• lijepo stoji = suits nicely

The short pronoun ti usually appears early in the clause because it is a clitic. Croatian clitics tend to go near the beginning of the clause, often in second position.

You might also hear variations for emphasis, but not all of them sound equally natural. For example:

• Mislim da narančasta kapa ti lijepo stoji — possible, but less natural in neutral speech
• Narančasta kapa ti lijepo stoji — very natural as a standalone sentence

So the given word order is a normal, idiomatic one.

Yes.

• Mislim da tebi narančasta kapa lijepo stoji...

This would sound more emphatic, as if contrasting you with someone else, or stressing that the speaker is specifically talking about you.

Compare:

• ti = neutral, unstressed
• tebi = stressed, emphatic

So the original sentence with ti is the most natural neutral version.

Yes.

In this pattern, the thing that suits someone is the grammatical subject:

• narančasta kapa = subject
• stoji = verb
• ti = indirect object in the dative

So literally, the structure is closer to:

• The orange cap stands nicely to you

But natural English says:

• The orange cap suits you nicely
• The orange cap looks nice on you

The same is true in the second clause:

• ljubičasta haljina is the subject of the omitted stoji

Yes, absolutely. A fuller version would be:

• Mislim da ti narančasta kapa lijepo stoji, a ljubičasta haljina ti stoji još ljepše.

That is grammatically correct. It is just a bit more repetitive.

Croatian often prefers the shorter version when the meaning is obvious:

• ...a ljubičasta haljina još ljepše.

So the original sentence sounds more natural and elegant in everyday speech.