Nonocross Level 21 is a 8×8 nonogram with the answer SMILE. The completed grid contains 52 filled cells out of 64 total — a very dense puzzle (81%). With most cells filled, the empty gaps are the key constraint — trace them carefully.
The puzzle is part of the Levels 1–60 range on the Nonocross Answers hub. Each number in a clue line represents one consecutive run of filled cells; runs are separated by at least one empty cell. The visual grid below shows the verified solution — the clue reference lists every row and column clue so you can cross-check your own attempt. Continue to Level 22 when ready.