Close To Becoming Inactive in Ranked

Inactivity notification in game is telling me I have 1 day left before decay begins.

Season ends in 1 day and 5 hours.

I'm Diamond III at 0 LP in Flex 5v5.

So, two questions:

1. Does the "1 day until decay" message mean LESS than 24 hours, or somewhere between 24 and 48?
2. If it's less than 24, can I go the 1 day and 5 hours without playing Ranked and remain at the same spot, or am I immediately going to be booted to Diamond II?

Thanks for the help!