Mismatch in number of columns noticed by W3C's HTML5 validator.
print '<table class="mapped">';
print '<col span="3">'; # should match first thead row
printf '<colgroup span="%d">', scalar @{ $versions{$_} } for @browsers;
print '<table class="mapped">';
print '<col span="3">'; # should match first thead row
printf '<colgroup span="%d">', scalar @{ $versions{$_} } for @browsers;
my $header = join('',
'<tr>',
my $header = join('',
'<tr>',