Book cover in the style of Russian Grimm's fairy tales for a story where a boy’s sister is cursed by Baba Yaga and turned into a cat. The boy and his sister (as a cat) should be the central figures, depicted with whimsical, fairy-tale characteristics. Include a mystical, snowy winter fairyland with frosty trees, shimmering snowflakes, and an enchanting magical forest in the background. Feature a wise, magical fox guiding them, adding an aura of mystery and charm. The style should be richly detailed with a dark, enchanting atmosphere. Use ornate, traditional typography for the title and author’s name. --niji 6