Fix flags for firefox and safari

[mckelveygreg]

Fixes 2 bugs:

• flag covers whole screen on firefox #110 Full page flag in firefox
• flag not visible in Safari #111 No flag in safari

I was not able to run this locally, but I tested by using these overrides in my code 🤷
Webpack wasn't able to find @mui/styles and react

[mckelveygreg]

@fnowacki Is there anything else I need to do for this to be merged?

[david-vendel]

Hello @mckelveygreg thank you for this fix. It indeed works well.
Seem like noone is maintaining this library anymore, and owners don't even care about it to give a merge permission for this repository to somoene from us.
So I got fed up, and since I need this to be fixed for my client project, I forked this library, fixed this bug and published it at:
https://github.com/justdvl/material-ui-phone-number-2
https://www.npmjs.com/package/material-ui-phone-number-2

I recommend everyone who needs this library but working, to make a simple switch. I will also actively maintain this version 2 library, I will make few more improvements in following days

[viclafouch]

This package (https://github.com/viclafouch/mui-tel-input) handles this problem, supports both React 17 / 18