Ultimately you can’t control when and how things go wrong but you do have some control over what happens. This is why progressive enhancement exists.
Monday, June 18th, 2018
Monday, February 25th, 2013
And this is why user-agent sniffing not a future-friendly technique. A new mobile browser comes along, and it has to spoof a fake UA string to all of these sites.
It’s a Red Queen arms race.