Why did my custom CSS stop working in Gecko theme settings?

[mth]

I am using Gecko theme, and writing custom CSS in the theme settings custom CSS sections. It was working ok before. Now suddenly some CSS are not working suddenly. I am writing CSS codes in the sections for mobile/deskptop to test, for example putting borders around elements. But these basic CSS are also not working.

Pls help me.

[LeanneJ12]

I am having a similar issue with the Gecko theme, suddenly none of my custom CSS is showing Live.