Child Theme for Picolihgt

I’m clear about how a child theme can prevent css and other changes from being lost if a new version of that theme is released.

However, I’ve made css changes to Picolight and haven’t added a child theme yet. Can I add a child theme NOW and use “@import url” to get theme files from parent theme–and be assured later if I update to a future version of Picolight that my changes won’t be lost?

Note: I’m planning to install the child theme–and all future style changes will be made before the next Picolight version is released.