Great app! here is some suggestions:
1- Please add "custom starting week date" option. I live in Iran and our weeks starts on Saturday.
2- Add workdays option in new habit menu. some habits only doable in worktime!
3- The Dark theme
4- Add custom colors for each habit.(random or selectable) like "google keep" app
5- In graphs you can add "from beginning" in time period selections.
this app has an fantastic idea and very good looking ui
(sorry for my english)