What is the fine-grained topic of the following text: Anyone with a rudimentary understanding of the '70s or (American Hustle in their Netflix queue, for that matter) can list a number of the decade's most significant trends — plunging necklines, wide-leg trousers, jumpsuits, an excess of glitter — most of which can be attributed to Saint Laurent and Halston. Only return the topic.
'70s Fashion Trends Influenced by Saint Laurent and Halston