In the fourth film adaptation of Little Women, starring Winona Ryder and Susan Sarandon, Louisa May Alcott's 1868 novel about four sisters coming of age proves that what's now in vogue may not be so new. The Marches Meg, Jo, Beth, and Amy are a vegetarian, socially conscious, liberal family, much like Alcott's own. ''It's certainly a feminist story,'' says director Gillian Armstrong, whose $15 million movie opens in December. ''In the past movies [made in 1919, 1933, and 1949], they're dewy, girly girls. But actually, they're vain and conceited and love each other, like sisters today.'' As the two oldest, Ryder, 22, and Trini Alvarado, 27, traveled back in time in more ways than one: Their makeup was all but invisible, and corsets were a necessary evil. ''When I look at how beautiful the clothes were, I'm sorry we don't make them that way anymore,'' says costume designer Colleen Atwood. ''But then I think of the way we live, and I say 'Thank God.'''