As first seen on blog "Black Dress Inspiration" here: ANOTHER LOOK WITH SKIRT
She is wearing tights similar here: Navy Super Opaque Tights
Always a favorite, these Italian-made tights are soft and superstretchy (so they won't bag out at the knees).
Junya Watanabe Pink Block-colour Tights
Express Swiss Dot Full Tights
Boohoo Mini Heart Tights