Complex sentence: Fin de siecle culture has been perceived to have influenced 20th century culture, such as Bohemian counterculture having similarities to punk counterculture in that both celebrate a romantic and willful sense of decay.
Split into simpler sentences: Fin de siecle culture has been perceived to have influenced 20th century culture. Such as Bohemian counterculture having similarities to punk counterculture that both celebrate a romantic and willful sense of decay.