Red, yellow, and green are familiar colors of traffic lights. And in Britain, the colors have long helped shoppers decide which groceries are good for them, at least in terms of how much fat, sugar and salt they contain. Supporters of the scheme say it's simpler than reading the fine print on pakages. But efforts to introduce the system across the entire EU were dealt a blow on Tuesday. Instead, the bloc plans to ensure that food manufacturers detail the actual contents of their products.