Grant Park
Sky Ferreira, Lollapalooza's grunge style star
Sky Ferreira, Lollapalooza's grunge style star

If there is a poster child for the return of 1990s-era grunge fashion, it's Sky Ferreira. The singer and model, who was born in L.A. but now seems to live all over, was a muse for Saint Laurent designer Hedi Slimane's "California Grunge" fall 2013 collection. And the designer tapped her to star in the label's pre-fall ad campaign, decked out in black lace, leather and studs.  So it was only fitting that Ferreira, 21, would hit this weekend's Lollapalooza festival in Chicago, which was born out of the post-punk, alternative rock and grunge music scene, having been created in 1991 by Jane's Addiction singer Perry Farrell. It's the same music...