Is a city's offer of judgment limited to the amount of reasonable attorney fees already accrued?

We need not decide this question, however, because the offer contained the additional, ambiguous language "costs now accrued and reasonable attorney fees as determined by the court." One could certainly conclude this fee provision is broader than the cost provision and might extend to those fees not already accrued. Thus, the limitation the City apparently intended is no longer clear and unambiguous. Furthermore, we have held that courts should apply the usual rules of contract interpretation to offers of judgment, Herrington v. County of Sonoma, 12 F.3d 901, 907 (9th Cir.1993), and these rules dictate that ambiguities be construed against the drafter. Id.