After some further investigation…
Bootstrap was loaded by default, which was affecting the style. I changed the default settings to prevent loading Bootstrap. You can still use Bootstrap, but you have to enable loading it manually under “Manage Plugin”. If you prefer to, you can style them yourself.
I hope you are reading this reply Marek!? I would be glad if you could confirm whether this solved your problem… Thanks!
BTW To show tables on your webpages or posts, you’ll need to load jQuery Datatables and jQuery Datatables Responsive scripts and styles. WP Data Access uses jQuery DataTables for this purpose. You can of course still use WP Data Access on the back-end without jQuery Datatables. In that case you can turn off loading jQuery Datatables and jQuery Datatables Responsive scripts and styles as well.