The classes applied to fields follow this pattern: field-type-[type] and field-name-[name]
This allows a theme to easily style a particular field or to style a particular type of field.
Unfortunately, the node edit form uses the exact same class names for the field form widgets. Completely different HTML (rendered field vs. form widget), but the exact same class. This is super problematic as any moderately complex field styling can break the corresponding field widget when adding or editing a node.
The classes on the node edit form's field widget containers are to "aid in theming", but they do the opposite. In order to style the field widgets, you first have to undo the styling for the rendered field and then apply the desired widget styling. Even if you don't want special widget styling, you still have to undo the rendered field styling. :-p
Zen 7.x-3.2 changes the classes used on the field widget wrappers by prepending form- to the class names. So they'd be: form-field-type-[type] and form-field-name-[name].
Upgrading from 7.x-3.1
If you were adding styles to the node edit forms, the classes around field labels and widgets have changed. You will need to alter your CSS selectors. A common way to style node edit forms is to use the .node-edit body class. Rules containing that class are more likely to need altering because of this issue.
