I prepared an image.

These are screenshots of errors.I am glad if you can help me.
Thank you very much.

Image for question [1]

I have this error when I want to be able to use upper case and lower case letters.

Image for question [2] 

I have this error when I want to change the font.

Error message at the top of the Screenshot

Japanese

<カスタマイズ中
追加CSS

保存する前に１個のエラーを修正してください。
[_]サイトを壊してしまうかもしれませんが、それでもアップデートしますか？

English

<Customizing
Additional CSS

There is 1 error which must be fixed before you can save.
[_] Update anyway, even though it might break your site?

I referred to this URL for translation. After I used “translate with Google”, I searched similar English words, I found this and thought it was the same meaning.

Customiser Additional CSS > reports error when using CALC ()
https://wordpress.org/support/topic/customiser-additional-css-reports-error-when-using-calc/

Thank you very much.