Hi Alex,
thanks for your question.
This is done with the “FixedHeader” plugin for the DataTables JavaScript library (see https://datatables.net/extras/fixedheader/)
Here are some instructions that I had given someone else to get it to work. I don’t know if this is still working and the JavaScript file in the download might not be the latest version, so you might need to update it. Anyways, the code in the PHP file should get you started so that you can see how it works in principle.
The necessary code is here: https://tobias.baethge.com/download/plugins/additional/wp-table-reloaded-fixedheader.zip
– Unzip the file and place the included folder (with 2 files) in your wp-content/plugins/ folder.
– Then activate the new plugin “FixedHeaders (Extension for WP-Table Reloaded)” from within your WordPress admin area.
– Go to the WP-Table Reloaded “Plugin Options” and add the following CSS code to the existing one:
.FixedHeader_Cloned table {
margin: 0!important;
}
– Now, for every table that you want fixed headers on, go to the corresponding post/page and extend the Shortcode of that table with one (or two) new parameters:
E.g.
[table id=1 /]
becomes
[table id=1 fixedheader=true /]
where the new parameter “fixedheader” will turn on the feature for the header row.
I hope that this still works.
Best wishes,
Tobias