I added css properties in the CSS style.css of my children theme, but NP don't use i', any css inside the css file style.css ionside wp-content/theme/mytheme/style.css nort working, but I would like...

Hi! I see that I can add a custom CSS to my page. But how can I add a CSS only for mobile devices?

No problem with adding custom CSS code until now, but it seems that the code I'm adding is being deleted / corrupted. I copy paste the code in "edit css" window when I open it again there's only one...