design problem on selecting a range of dates backward

[shayan1999]

I found this bug when I was testing this library on sand box I wanted to choose a range of dates it works correctly when you select days incrementally but But when you do the opposite you can see selecting days design has some problems (it goes out of range)

Steps to reproduce the behavior:

1. Go to Sandbox
2. Click on the date picker and then after selecting a date select an older date
3. now you can see the problem

I am currently using this library for one of my projects so I want to make a contribute on your project and fix it if you confirm this bug.