I hadn’t the previous version or the version where this version relies on.
While waiting an answer, I started to create my own default.css, based on the output generated by the plugin while activated in a test environment.
At the same time, I changed some of the code to have the output seamless integrated in my website project.
I also found a problem while using the function to show date and time below a post. I found out ‘the system’ has problems to use file names with spaces and ampersants. I don’t know if this specific for this plugin or a general WordPress issue.
For this plugin, I could make a work-around:
Step 1: Rename the two .css files to a file name without spaces and without ampersand
Step 2: De-activate and re-activate the plugin.
I used “datetime.css” and “justthepost.css” as new file names.