When it comes to new rules for marketing so-called light cigarettes, tobacco companies plan to honor the letter of the law — but to shade the truth, critics say. Come June, under the new federal tobacco law, cigarette companies will no longer be allowed to use words like “light” or “mild” on packages to imply that some cigarettes are safer than others. But in a move that critics say simply skirts the new rules, tobacco companies plan to use packaging to make those same distinctions: light colors for light cigarettes.