The noun levity means a behavior of treating serious matters a non-serious way. It also means the quality of being light.

Synonyms are frivolity, giddiness, silliness, or hilarity.

The word origins from French (1560s) levite meaning “want of seriousness, frivolity” and from Latin levitatem meaning “lightness” literal and figurative “light-mindedness, frivolity” from levis “light” in weight.

Maybe a little levity would help in this very serious situation.

She is known for her levity and high spirits that offends the traditional elderlies.

His unsuccessful attempt at levity made the matters worse.