Centering the single file upload field button

How do I center the "choose file" upload button here?

https://www.jotform.com/build/73258991513868

It is too complex to customize the native file upload field since every browser has different file upload styles. Example on Firefox, it has a different button size and a text.

I suggest to turn on the multiple files option so you can customize the button further like aligning it in the middle. Here's how to enable multiple files option.

Thanks for the option. I just tried it and it's not ideal in terms of user-experience and functionality (I don't want to receive multiple photos each time).

As all users will be on mobile, is there a way to customise it for the most popular phones/browsers? eg only for Safari and Chrome?

Even latest browsers don't have the capability to do so. The native file upload style is browser inherent. There is a workaround but there are so many downsides like the file can't be seen in the upload field after you browsed it from your computer. If you like, inject this CSS codes to your form https://www.pastiebin.com/view/5a287a161b62e. 

By the way, the multiple file upload has limits. You can limit it to 1 file if you want.