The flag of Sweden is a Scandinavian cross that extends to the edges of the flag.
This Scandinavian cross represents Christianity. The design and colours of the Swedish flag are believed to have been inspired by the present Coat of arms of Sweden of 1442, which is blue divided quarterly by a cross pattée of gold, and modelled on the Danish flag. Blue and yellow have been used as Swedish colours at least since king Magnus Birgersson’s royal coat of arms of 1275. Wikipedia