How to allow for manual HTML & CSS changes?
go to:
/admin/config/content/ckeditor/edit/Advanced (for Filter HTML)
/admin/config/content/ckeditor/edit/Full (for Full HTML)
Then under Advanced Content Filter, select disabled.

If the above does not do it, depending on which one you are using (filter or full html) You need to go to
/admin/config/content/formats/filtered_html
OR
/admin/config/content/formats/full_html
Uncheck the correct faulty and chopped off html box.