keeping it simple is indeed the current motto :)

I'm ok with the "click on the pop-up then type" feature being only discoverable from the documentation as that's an advanced user feature, but maybe we could have a small help link at the bottom of the popup to display a short explanation of keyboard feature (I opened a issue for it https://github.com/maxlath/time-capsule/issues/3 ).

In the case the browser is opened after the expiration time, the expired bookmark is directly opened: hope that registers as graceful :)

[2023 Edit]: the new version should make it easier to program capsules to open on a very specific date, see the "advanced" mode