Styling forms is hard. Wouldn't it be great if there was a Sass extension that would do just that, configurable to fit your needs? Here's a concept for Sass Forms (which needs a fancier name, obviously). Sass Forms comes with sensible defaults.
Because we only want to fight over Sass and the resulting CSS, we'll start with markup from SimpleForm, a gem wildly used in Rails projects (but you could just hand-code said markup as well). By doing this, Sass Forms will immediately work in thousands of web apps. By making the input wrappers, etc configurable, like SimpleForm does, it can be used in even more projects.
Later on, Sass Forms can also support Formtastic markup (or any other gem with predefined output). By tweaking just a few configuration variables, it's also great for forms with custom markup.