If a category title contains a period, then the period and the rest of the title is excluded from the category name in the category overlay.
1. Visit https://en.m.wikipedia.beta.wmflabs.org/wiki/Dog
1. Add the page to a category that contains a period.
1. Open up the categories: https://en.m.wikipedia.beta.wmflabs.org/wiki/Dog#/categories
1. Verify the full name is shown including text after the period