You produced a mask by a strata shader, afaik. That is hard by definition, so can't be subtly changed. If you want to change the widths of those terraces or distance between them, you should do so in the strata shader.
Better control can be gained by using a 100% soft simple shape, and adding a series of color adjusted steps. I made you a small sample. Instead of the color adjust, it's better to use a smooth step, as they have soft edges. Further slope control can be had by using a gain + scalar.