The sun hasn't exactly set on Solar Planet, but anxiety over the fate of the Arlington tanning salon has been running high ever since a "tan tax" took effect Thursday. One of the less publicized measures in the new health-care law, the tax imposes a 10 percent surcharge on the use of ultraviolet indoor tanning beds. Supporters -- including the Obama administration, congressional Democrats and dermatologists -- have argued that the tax will raise an estimated $2.7 billion toward the cost of expanding health coverage to the uninsured, while discouraging a practice that increases the risk of skin cancer by...