Juul Labs, the vaping company that has long insisted it never marketed its products to teenagers, purchased ad space in its early days on numerous youth-focused websites, including those of Nickelodeon, the Cartoon Network, Seventeen magazine and educational sites for middle school and high school students, according to a lawsuit filed Wednesday by the Massachusetts attorney general. The suit, brought against Juul by the state’s attorney general, Maura Healey, presents some of the starkest evidence to date that the company was targeting young nonsmokers during its launch period, from June 2015 through early 2016. According to the lawsuit, Juul rejected an initial marketing proposal by a marketing firm it had hired, Cult Collective, that would have branded it as a technology company with a target audience of adult smokers. The proposal that was rejected featured images of outdated technology like clunky telephones and joysticks, with a picture of a Juul device and the words, “Smoking Evolved.” Instead, the lawsuit says, Juul dropped the Cult Collective, and hired an in-house interim art director to produce “Vaporized,” the youth-oriented campaign, featuring beautiful models in pr...