This sub-table lost the space between border due to border-collapse, and also might receive extra padding if main <td> has some padding
Main 4
Sub 5-1
Sub 5-2
5-3
This sub-table does not declare border-collapse, and while this retains space between table cells, this adds even more border-spacing between <table> and <tbody>
Main 6
Sub 7-1
Sub 7-2
7-3
Best I could do using margin:-3px; to offset the border-spacing, padding:0px; to remove padding set by .infobox class, but this does not work well in narrower sub-boxes like below
7-4
This might be good if you really use this as a sub-section and do not mind the shrinkage, but bad if you use this for collapsible table section
Main 8
Sub 9-1
9-2
This table is narrower by 6px when collapsed :( :( :( :(
