That light blue background is actually an additional border that the studio attached the photograph to. Attaching the photograph to an additional background was not uncommon (though I’ve never seen this color used before) in the era of daguerrotypes, ambrotypes, and tintypes (the hard images). Once photography advanced to cartes-de-visite and cabinet cards being the norm, the fact that they were paper prints eliminated the need for an additional border, made from a separate sheet of paper.
The pose is typical of the 1840s-late 1880s, where the body was made to appear as if only asleep, and was a denial of death in many photographs. The Burns Archive has three books of “Sleeping Beauty” from during and around this time that have some very unsettling images in them.