colgroupにborderが反映されない border MDNborder Chrome (103)Firefox (103) HTML <table> <caption></caption> <colgroup span="4"></colgroup> <colgroup> <col></col> </colgroup> <thead> <tr> <th>1 <th>2 <th>3 <th>4 <th> </tr> </thead> <tbody> <tr> <td>1 <td>2 <td>3 <td>4 <td>no </tr> <tr> <td>1 <td>2 <td>3 <td>4 <td>yes </tr> </tbody> </table> css table{ border-spacing:0; width:50%; text-align:center; } colgroup:nth-of-type(1){ border: 2px solid blue; background-color:rgb(255 0 0 / 0.3); }

bordercolgrouptable