Need help with a slide-in bottom lid design

Hi everyone! I’m designing a slide-in bottom lid for a bottle. There’s a 0.2mm gap for the lid to fit smoothly, but I’m worried it might fall out. I feel like it might need a simple mechanism to keep it in place, but I’m not sure what would work best. Any tips or ideas would be really helpful. Thanks!

Did you consider using an O-ring?

What the purpose/ use of the lid? Easily removable often or occasionally? A simple round wire circlip that fits in a groove would work if you need only remove it occasionally.