HTML and CSS Reference
The table as rendered by Opera is shown in Figure 10-6 . Notice that
the rules after the table header and before the footer are thinner than
the borders around the other table rows. This happened because we in-
cluded the special rules=groups attribute to the <table> tag. You may
obtain similar effects by specifying rules=rows or rules=all .
Figure 10-6. Use HTML 4/XHTML table tags to specially
section your tables
Long tables often benefit from thicker rules every few rows, making it
easier to read the tables. Do this by grouping the rules in your table with
several <tbody> tags. Each set of rows contained in a single <tbody> tag
will have thicker rules before and after it.