I recommend a visit to the library in the garden a "Alvar Alto" like building that has a lot of pleasant places for reading open tue-thu 1 pm - 5 pm and Fridays 1 pm until 4 pm
Its café, Cafe Blom, is one of my favourite Stockholm summer time hideaways, lovely quiet courtyard and garden with Picasso art. Have some rose wine, tapas and cakes. Great prices.