Design challenges for an application supposed to work in offline environment

I know question is too broad to answer, but I expect hints or area where I can research so please don't close this question.

I need to design a client server application that can work in offline mode as well. Consider sales/marketing executives going on sites.

Which technology suites best keeping client as light as possible.

I am thinking in direction of

Server

WCF Service , SQL Server, Web application

Client

Web application using Indexdb - Same web app hosted on server

or shall I use window application with sql server express - enabling merge replication