HTML colgroup element

The <colgroup> HTML element defines a group of columns within a table.

The <colgroup> should appear within a <table>, after any <caption> element (if used), but before any <thead>, <tbody>, <tfoot>, and <tr> elements. Only a limited number of CSS properties affect <colgroup>: background : The various background properties will set the background for cells within the column group. As the column group background color is painted on top of the table, but behind background colors applied to the columns (<col>), the row groups (<thead>, <tbody>, and <tfoot>), the rows (<tr>), and the individual cells (<th> and <td>), backgrounds applied to table column groups are only visible if every layer painted on top of them has a transparent background. border: The various border properties apply, but only if the <table> has border-collapse: collapse set. visibility: The value collapse for a column group results in all cells of the columns in that column group not being rendered, and cells spanning into other columns being clipped. The space these columns in the column group would have occupied is removed.