The article doesn't explain all tricks they use. A media query is used to apply the stylesheet selectively to small window sizes. That stylesheet splits the tab

The article doesn't explain all tricks they use. A media query is used to apply the stylesheet selectively to small window sizes. That stylesheet splits the table into multiple ones. The original table's border is removed, and every tr is styled to look like a table by giving it a border. tds are turned into rows by setting display:block. The td rows are given row headers using pseudo elements, which pulls their content from an attribute on the corresponding td.