Mislim da taj remen ne stoji dobro uz plavu haljinu.

In Croatian, mislim da... is the normal way to say I think that... or simply I think....

• Mislim = I think
• da = that
• Mislim da taj remen ne stoji dobro... = I think that this belt doesn't go well...

Unlike English, Croatian very often keeps da in this kind of sentence.

Literally, stajati / stoji can mean to stand, but in this sentence it has a different, very common meaning.

Here, stoji dobro uz means something like:

• looks good with
• goes well with
• suits

So:

• Taj remen ne stoji dobro uz plavu haljinu. = That belt doesn’t go well with the blue dress.

This is a useful expression for clothes, colors, and style.

Taj means that, and it has to agree with the noun it describes.

• remen = belt
• remen is masculine singular
• so the demonstrative also has to be masculine singular: taj

Examples:

• taj remen = that belt
• ta haljina = that dress
• to odijelo = that suit

So taj is used because remen is masculine.

Because after uz, the noun here is in the accusative case.

The dictionary form is:

• plava haljina = a blue dress / the blue dress (nominative)

But after uz, it changes to accusative:

• uz plavu haljinu

Both the adjective and noun change:

• plava → plavu
• haljina → haljinu

So:

• nominative: plava haljina
• accusative: plavu haljinu

In this sentence, uz means with in the sense of together with / in combination with / alongside.

When uz is used as a preposition like this, it normally takes the accusative.

So:

• uz haljinu = with the dress
• uz plavu haljinu = with the blue dress

This is why you see plavu haljinu, not the nominative form.

In Croatian, ne is usually written separately from the verb.

So:

• stoji = it goes / it stands
• ne stoji = it does not go / it does not stand

That is normal Croatian spelling.

A learner should get used to patterns like:

• ne znam = I don’t know
• ne mogu = I can’t
• ne stoji = it doesn’t go well

Dobro is an adverb here, meaning well.

It modifies stoji:

• stoji dobro = looks good / goes well
• ne stoji dobro = doesn’t look good / doesn’t go well

So the idea is not just that the belt and dress are together, but that they don’t match well.

Yes. That would still be correct.

• taj remen = that belt
• remen = the belt / a belt, depending on context

Using taj makes it more specific, as if you are pointing out a particular belt.

So:

• Mislim da remen ne stoji dobro... = more general or context-dependent
• Mislim da taj remen ne stoji dobro... = specifically that belt

This word order is very natural and neutral.

Breakdown:

• taj remen = subject
• ne stoji = verb
• dobro = adverb
• uz plavu haljinu = prepositional phrase

Croatian word order is more flexible than English, so other orders are possible for emphasis. For example:

• Mislim da uz plavu haljinu taj remen ne stoji dobro.

This puts more focus on with the blue dress.

But the original sentence is the most straightforward and natural for a learner.

Yes. Remen is the standard word for belt.

It can refer to:

• a clothing belt
• a strap
• sometimes even a mechanical belt, depending on context

In this sentence, because of haljinu (dress), it clearly means a clothing belt.

The basic form is haljina, and nouns ending in -a are very often feminine in Croatian.

So:

• haljina = feminine singular nominative
• accusative singular becomes haljinu

The adjective must match it:

• plava haljina
• plavu haljinu

This kind of agreement is very important in Croatian:

• noun + adjective must match in gender, number, and case

Not always. Uz has several related meanings, depending on context, such as:

• next to / by
• along
• with / together with

In clothing and style contexts, uz often means with in the sense of matching or combined with.

So here:

• uz plavu haljinu = with the blue dress

But in another sentence, uz could mean something more physical, like next to or alongside.

A Croatian speaker would normally understand it as a comment about style or matching clothes:

I think that belt doesn’t go well with the blue dress.

The sentence sounds natural and conversational. It suggests that the speaker thinks the belt is not a good visual match for the dress, probably because of color, style, shape, or overall appearance.