Questions & Answers about Dat gordijn is mooi, maar het is niet groot genoeg.
Why does genoeg come after groot?
When modifying an adjective like groot (large), the word genoeg (enough) must always come immediately after the adjective. Luckily, this works exactly the same way as in English!
Why do we use dat and het for the curtain?
The word for curtain, gordijn, is a neuter noun (het gordijn). Therefore, we must use dat to say "that" curtain. In the second half of the sentence, we use the pronoun het (it) to refer back to this neuter noun.
Could I put niet at the very end of the sentence?
No, in this case niet must come right before the adjective phrase it negates (groot genoeg). You are specifically saying it is not large enough, so niet stays glued to the front of that phrase.
Does the word maar affect the word order in the second part of the sentence?
No. Maar (but) is a coordinating conjunction. This means it simply connects two normal main clauses. The second clause keeps its standard subject-verb order (het is), without pushing the verb to the end of the sentence.