Вопреки тому что паспарту тёмное, чёрный кант хорошо видно.

It means despite the fact that or even though.

So the first part of the sentence,

Вопреки тому что паспарту тёмное

means something like:

Despite the fact that the mat is dark / Even though the mat is dark

This whole expression introduces a contrast: you would expect the black border to be hard to see, but in fact it is clearly visible.

A useful note: вопреки тому что is a bit more formal or literary than very common alternatives like хотя or несмотря на то что.

Because вопреки normally takes the dative case.

For example:

• вопреки правилам = contrary to the rules
• вопреки ожиданиям = contrary to expectations

In вопреки тому что, the word тому is the dative form of то. After that, что introduces the clause.

So the structure is basically:

• вопреки
  • тому
    • что-clause

This combination works as a fixed conjunction meaning despite the fact that.

Because паспарту is an indeclinable noun that is normally treated as neuter singular in standard Russian.

So the adjective agrees with it in gender and number:

• паспарту тёмное
• not паспорту тёмный

This is common with some borrowed indeclinable nouns in Russian: even though the noun itself does not change, adjectives agreeing with it still show gender and number.

So here:

• паспарту = neuter singular
• тёмное = neuter singular adjective

Because the sentence begins with a subordinate clause, and then comes the main clause.

Structure:

• Вопреки тому что паспарту тёмное, = subordinate concessive clause
• чёрный кант хорошо видно. = main clause

Russian uses a comma to separate these two parts, just like English often does with although/even though clauses.

Grammatically, in this sentence it is better to think of чёрный кант as the object of an impersonal construction.

The key part is:

чёрный кант хорошо видно

This means the black border is clearly visible / you can clearly see the black border.

With видно used this way, Russian often has an impersonal structure, where the thing seen is in the accusative case.

The tricky part is that кант is an inanimate masculine noun, and for that type of noun:

• nominative singular = кант
• accusative singular = кант

So the form looks the same.

That is why it can look like a subject even though the construction is impersonal.

A comparison helps:

• Чёрный кант хорошо видно.
• Чёрную рамку хорошо видно.

In the second example, рамку clearly shows the accusative.

Because видно and виден are two different constructions.

1. ...хорошо видно

This is an impersonal construction.

It means:

• ...is easy to see
• ...is clearly visible
• you can clearly see ...

Example:

• Чёрный кант хорошо видно.

2. ...хорошо виден

This is a construction with the short-form adjective виден, which agrees with the noun.

Example:

• Чёрный кант хорошо виден.

This also means the black border is clearly visible.

So yes, Чёрный кант хорошо виден is also possible.

The difference is mainly grammatical:

• видно = impersonal
• виден = agrees with кант as a masculine singular noun

Both are natural. Learners often meet видно very often in everyday Russian.

Here хорошо is best understood as clearly, plainly, or easily.

So:

• хорошо видно = can be seen clearly
• not literally just well visible in an awkward English sense

Russian often uses хорошо with verbs and predicative words in places where English prefers adverbs like clearly or easily.

For example:

• Отсюда хорошо видно море. = You can see the sea clearly from here.

It is correct, but it sounds somewhat formal or written.

More common alternatives would be:

• Хотя паспарту тёмное, чёрный кант хорошо видно.
• Несмотря на то что паспарту тёмное, чёрный кант хорошо видно.

All three are grammatical, but they differ a bit in style:

• хотя = very common, simple, neutral
• несмотря на то что = common, slightly more formal
• вопреки тому что = more bookish/literary

Yes, but it is natural Russian word order.

The sentence starts with the contrast clause:

• Вопреки тому что паспарту тёмное, ...

Then the main information follows:

• чёрный кант хорошо видно

Putting чёрный кант before хорошо видно is normal in Russian and helps present the thing being discussed first.

Russian word order is more flexible than English, so several versions are possible depending on emphasis. For example:

• Хотя паспарту тёмное, чёрный кант хорошо видно.
• Чёрный кант хорошо видно, хотя паспарту тёмное.

The original version is perfectly natural, especially in written description.

Yes. A simpler version would be:

• Хотя паспарту тёмное, чёрный кант хорошо видно.

Or, if you want the agreeing adjective construction:

• Хотя паспарту тёмное, чёрный кант хорошо виден.

These are easier for many learners because:

• хотя is a very common conjunction
• виден makes it clearer that кант is the thing being described as visible

But the original sentence is still fully correct and useful to know.