"Generally speaking, it doesn't matter whether a medical certification is written on your preferred form or on the back of a bar napkin. So long as the document is signed by a health care provider, and is 'complete' and 'sufficient' in the sense that it provides the employer with all of the information needed to determine if the leave is covered by the FMLA, then the certification should be accepted.... because the employee is responsible for providing the employer with complete and sufficient medical certification supporting the need for FMLA leave, the employee also is on the hook to pay the fee ... Not the employer."