Created Child Theme for Twenty Twelve by creating child theme folder and copying entire Style.Css of parent to same. Edited header to reflect child theme.
When I check new theme the appearance had changed and menus had lost drop down.
Are there other files (e.g. css) required to duplicate the theme before I can start altering it?
I am a newbie to WordPress developing ideas on laptop with Desktop Server for a club i am a member of (not working in wordpress as my profile says, but that's another issue!)