Check if the look of table style can be improved

Check if the look of table style can be improved.

Maybe there is an easy way to improve how tables look in rich text.

https://doc.qt.io/archives/qt-5.8/richtext-html-subset.html
We have to use CSS 2.1
https://stackoverflow.com/questions/25411539/restricted-to-css-2-1-can-i-ensure-that-one-border-in-a-table-shows-on-top-of