my $s = do {local $/=undef; <DATA>};
while(1){
  my $matched = 0;
  $matched ||= $s =~ s#<span style="font-weight: bold;">(?!.*?<span)(.*?)</span>#<b>$1</b>#sgi;
  $matched ||= $s =~ s#<span style="font-style: italic;">(?!.*?<span)(.*?)</span>#<i>$1</i>#sgi;
  $matched ||= $s =~ s#<span style="text-decoration: underline;">(?!.*?<span)(.*?)</span>#<u>$1</u>#sgi;
  last unless $matched;
}