Ali has equal numbers of yellow and dark blue marbles. Ali places his marbles in boxes A, B, and C, each of which is empty, according to the following rules:

• All of his yellow marbles; He puts them in boxes A, B, and C, proportional to 3, 4, and 6, respectively.
• All of his dark blue marbles; He puts them in boxes A, B, and C, inversely proportional to 3, 4, and 6, respectively.

When the number of marbles is the smallest, how many fewer yellow marbles in box B than the dark blue marbles?