Symfony version(s) affected: 4.1.x
Description
When using the box or box-double Table styling, regular tables are rendered fine, but tables with nested TableCells using colspan break the layout.
How to reproduce
Using this code from the docs (plus a style):
$table = new Table($output);
$table->setStyle('box');
$table
->setHeaders(array('ISBN', 'Title', 'Author'))
->setRows(array(
array('99921-58-10-7', 'Divine Comedy', 'Dante Alighieri'),
new TableSeparator(),
array(new TableCell('This value spans 3 columns.', array('colspan' => 3))),
))
;
$table->render();
results in this:

compared to this with the default styling:
