Adjust font size dinamically

[hunminkim98]

Hello, Dr. David. Thanks for the great work you always do.

After doing some testing, I realized that it would be nice to be able to adjust the font size dynamically, so I created this pull request to make it relatively simple. When you get a chance, I'd appreciate it if you could look at it.

Several test result: 3840 x 2160: font size = 1

2704 x 1520: font size = 0.7

1376 x 910: font size = 3.2