Crossing Hours per phum9679

Crossing Hours is a compact availability board for one day in one time zone. Add two to five people and up to four free intervals for each person. The popup draws each person's free hours on a 24-hour rail and highlights the exact intersection on a separate Together rail. It identifies the longest common window, reports its duration, and counts the shared windows. Intervals are calculated to the minute; adjacent or overlapping intervals belonging to one person are combined before the group intersection is found. Incomplete or backward intervals are explained rather than treated as available time. The board is intentionally manual: it does not read calendars, browser tabs, contacts, meeting invites, or other websites, and it does not send invitations or notifications. The roster and entered intervals remain in localStorage in the Firefox profile so the board is available when the popup reopens. No account or internet connection is required. Overnight windows and different time zones are outside this version's scope.