Simplify the following text for a Grade 9 native English-speaking person.
Original: The band 's musical style evolved from black metal to a cleaner and more `` produced '' amalgam of gothic metal , symphonic black metal and other extreme metal styles , while their lyrical themes and imagery are heavily influenced by gothic literature , poetry , mythology and horror films .
Simplified: Some people say the bandâ musical style is black metal , others say that it is gothic metal , extreme metal , or many other different styles .