The Groups.io compact display of times or dates works well to save screen space but could be improved for use on any mouse-less display such as a tablet or a smartphone.
At present, the time of day is shown provided it is after midnight (in the preference timezone, usually), and just the date if earlier. The full date and time is shown as a tooltip if the mouse or similar pointer hovers over the area. On a tablet or phone with no pointer, though, a time within yesterday is not visible. I can't easily judge at breakfast time whether a thread was added to early yesterday evening (when I read it), or late in the evening (which I would like to look at).
I suggest that the "today" format should be used for date-time values up to 22 hours old, rather than those before local midnight. This would convey a little more information without ambiguity and without using more screen space. (I suggest 22 hours, rather than 24, to allow for daylight saving time changes and a bit.)
The same change could usefully be applied to the step between month+day and year date displays: change at 12 months (or possibly a little less, above) old, not on New Year's Day. It's clear enough today (in June) that July 4 means last year, not next month.
Worth adding - Groups.io provides an excellent service. Thank you!
- Mark, Cambridgeshire, UK