Screenwriting (With Offline Mode) for Chromebooks?

Hi folks,

My girlfriend was considering a Chromebook as a light and portable machine for basic use, but the one requirement that might make it unfeasible is a need for some sort of screenwriting solution that features an offline mode.

I've looked at Celtx Edge (doesn't work offline) and Adobe Story (no offline mode either, except via the AIR app). Anyone know of an app I missed or a workaround I can consider?