Mary Steenburgen is remembering late Book Club costar Diane Keaton as a style icon who took Hollywood by storm. "This is how I will remember you. Dueling photos, you donned in your beloved polka dots, making me laugh and me, full of love and mad respect for your wild and unique artistry," Steenburgen, 72, captioned a series of photos of Keaton wearing her signature tailored outfits via Instagram on Wednesday, October 15.