Wow now this was weird.
I tried doing as you've said above and when I clicked save, it said no such theme found or something similar. I checked again and theme was there.
Then I went to update the theme and it said there was update available for the theme but this did not show up under the 'updates' section. So I updated the theme which removed a lot of my custom edit. But everything works now. Funny thought because the update replaced the files with the same files.
This is the same update which has been in effect for weeks now. nothing changed.
Weird but thanks for the help.
BTW, I didn't have to remove any of the CSS code as you said, it's all still intact.