They leave it vague; I've included the text from the offer letter below. It seems to imply that they expect the employee to pay the company if they leave before 30 days, but I'm not a 100% sure on my interpretation.
Termination at will: This Contract may be terminated by either the Company or you
without cause by serving a written notice of such termination 30 days prior to the date of
termination or payment in lieu thereof. In the event of termination by the employee
without notice or payment in lieu thereof, the Company shall be entitled to recover all
costs and expenses incurred in enforcing this Contract including attorney’s fees and other
reasonable expenditure

