Easy:

for my $line (split /\n/, $content){
    # Insert your code here
}
[download]

Personally, I prefer to slurp HTML into a single string and then use regexes to do whatever I need to it. HTML entities are often split across multiple lines, so treating it line-wise is problematic.

-- 
Education is not the filling of a pail, but the lighting of a fire.
 -- W. B. Yeats