Enqueue styles after a plugin

Note that cForms is hooking into wp_head, and you’re attempting to hook into wp_enqueue_scripts. The wp_enqueue_scripts hook is fired inside the wp_head hook (at priority 0, IIRC).

So, your stylesheet is being enqueued at wp_head, priority 0, and the cForms stylesheet is being enqueued at wp_head, priority 10. Since it outputs later, it is taking precedence over yours.

The solution is to use the same wp_head hook, with a lower priority (i.e. a number higher than 10), for your stylesheet.