How should I overlay a grid on a LeafletJs Map?

I have a LeafletJs Map with a Lat / Lon graticule. However what I would like at this point is to overlay a grid on the map with a fixed number of rows & columns (say, 19 rows and 17 columns), where the little rectangles that make up the grid would not change size as I zoom in and out on the map. How would I do that?