I guess, lastly I came to the solution by myself. It’s a good idea to build tables with flexible columns with percent values. But it’s only one condition for good results on small viewports. The other one is to reduce the font sizes. If you keep the original sizes, there’s not enough space for the content and an overflow rule will take place to hide the rest. But when I reduce the font sizes the table design changes, too. So I will duplicate all of the desktop table CSS and customize the font sizes, the padding values and columns widths in a @media definition.