Walmart, the nation’s largest retailer, has been long known for its basic socks, T-shirts and pull-on pants. Now, it’s aiming to be a destination for affordable stylish fashion for middle America so it can take a bigger space in customers’ closets. The Bentonville, Arkansas-based discounter has been making sweeping changes to the shopping experience _ adding mannequins and colorful displays of its clothing, while bolstering its fashion to include casual work wear like cargo pants and trendy dresses. It’s also brought in more than 1,000 brands like Reebok, Justice, and Chaps and partnered with celebrities like Sofia Vergara for a jeans line.