ref: 1380b55b5b9b5a841f3375f6c3f614105f1b6884
dir: /html/pattern.html/
Pattern <p> Fill in the grid with a pattern of black and white squares, so that the numbers in each row and column match the lengths of consecutive runs of black squares. <p> Left-click in a square to mark it black; right-click (or hold Ctrl while left-clicking) to mark it white. Click and drag along a row or column to mark multiple squares black or white at once. Middle-click (or hold Shift while left-clicking) to return a square to grey (meaning undecided): dragging like that can erase a whole rectangle, not just a row or column.