Well CodePen lets me see my editing live, so when I make a change in my code I can see exactly what I did right there.
You can get this feature with any real text editor. It’s called ‘live reload’. Also, I would definitely recommend a full-fledged text editor. TextMate seems to be popular among the Mac crowd. Sublime Text 2 is popular with everybody. Vim is popular with Linux people. All of them support ‘live reload’ AFAIK.
Do you use any sort of local virtual server? For testing? Or are you just coding static HTML + CSS?