CSS EDITOR Plugin doesn't work

I use the CSS Editor plugin for adding my own CSS but after save change my code is incorrect. What can I do with this? my CSS is 100% correct but the plugin removes some codes. The tag < s t y l e > is created in the HTML file and it has the <!-- in it.
any suggestions for me, please.

thank you

Those comment lines shouldn’t do anything harmful to your styles: those HTML comments are ignored within a stylesheet. They’re there just because they were necessary in (very) old browsers.

thank you very much for your help