In version 0.7.0-beta of the Exchange extension, the above CSS rule has been included. This should cause the last column of the table to expand to the remaining available size, for most themes. Please see the full release notes here: https://www.dashed-slug.net/static-exchange-templates/
I reply to all queries on the forums and via email, once per day, Monday to Friday (not weekends).
If you are new here, please see some information on how to ask for support. Thank you!