Age calculator app solution

Hello again, here I am to submit the latest challenge by frontend. I finally get a hang of making responsive CSS and there are many I learned in this challenge, especially the date function in JS. Also this is my first time trying @keyframes, it's fantastic.

I only have one problem though, when I open the app via Safari, some date can't be calculate and return NaN. However when I try in both Firefox and Chrome, there are no problem at all. I'm so confused, any advice would be highly appreciated.

Thank you