(?s)applies the following effective flags to the remainder of the pattern: gms s modifier: single line. Allows a dot to match line terminators
<!--the literal text <!-- \s*a Unicode whitespace character, repeated any number of times
\*the literal * (4210 / 528 / 2A16)
\s*a Unicode whitespace character, repeated any number of times
stylethe literal text style (case sensitive) \s*a Unicode whitespace character, repeated any number of times
.+?any Unicode character, repeated at least once
<!--the literal text <!-- \s*a Unicode whitespace character, repeated any number of times
/stylethe literal text /style (case sensitive) \s*a Unicode whitespace character, repeated any number of times
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string