Some awesome advice in this piece from Dean Vipond. My favorite recommendation (naturally):
This isn’t the time to get precious about your favourite design and development tools. Use progressive enhancement as your philosophy. Your service might have to be accessed on old devices in hospitals with outdated tech or unsupported operating systems. HTML+CSS is your best bet to ensure that the service can be accessed in unlikely scenarios you’ve never even considered. Do you want to take that risk at a time like this? Nope, me neither.