Gravity Forms v1.7.1 is now available via automatic update and the downloads page. This is a single fix release. It does not fix a bug in Gravity Forms. It implements a workaround to resolve a conflict caused by shortcomings in plugins that implement script and stylesheet minification such as W3 Total Cache, WP-Minify, etc.
In order to workaround the limitations of plugins that implement minification we had to change how we output CSS. These plugins choke on CSS when it implements @import statements which is commonly used to organize, manage and load CSS files. The end result is these plugins do not minify the Gravity Forms stylesheet and because they hijack the WordPress enqueue process the styles are never output on the page. The end result is the user thinks Gravity Forms is broken when in fact it is minification that is broken.
For now we have reverted to enqueuing each of the CSS files individually rather than using @import to load them from within the master stylesheet. We will be looking into ways to refine this going forward.