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

On the page:
Overview => User and Participant Management => List of All User Logins

The dates in the right-hand column ("Last login at" etc.) might be marked in different colors. What does that mean?

The colours do not really mean that much.

If the date "Last login at" is green, the user is probably still logged in as he has not log out yet. But he may also have closed his 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 date" 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.