Age calculator app that changes the input

What are you most proud of, and what would you do differently next time?

It changes the input of an invalid valid date. The user cannot input a date beyond today, as it changes back to the current date.

What challenges did you encounter, and how did you overcome them?

Had a hard time figuring out how to tackle the problem in where the user inputs a number that has to be a valid date.

a) The user cannot put a date in relative to month. i.e. Feb 30 b) Where the day input automatically updates whenever the month has changed, if that day input is higher than the max days of the month. c) Leap year

What specific areas of your project would you like help with?

I tackled invalid dates differently from the challenge, because I like the idea where the user is auto corrected with valid dates. Though I am not very sure if it is practical in real life situations.

Any kind of criticism is welcome! Please point out any problems!