Complex sentence: Usually, their lyrics talk about sadness, loneliness, jealousy and desire: this tragic contents usually contrast with the music, which normally is up-tempo, disco-oriented, but they have recorded great downtempo songs too.
Split into simpler sentences: Usually, their lyrics talk about sadness, loneliness, jealousy and desire. Their music is usually up-tempo, disco-oriented, but they have recorded great downtempo songs too.