Colours of dates on the page "List of All User Logins"

On the page "List of All User Logins":
Overview => User and Participant Management => List of All User Logins
...some of the dates in the right-hand column ("Last Login at" etc.) are marked in different colors.
What does that mean?

The colors don't really have much meaning.

If the date "Last Login at" is green, users are probably still logged in as they have not logged out yet. But they may also have closed their browser without logging out.
Please note that sessions are usually closed after max. 5 hours, even if a user did not log out.

If the "Logout at" is shown in red, the user has logged out at that date and time.

The "Last Action" date shows the last ConfTool page access of the user.