In an unexpectedly tight runoff, Kolinda Grabar-Kitarovic, a conservative challenger, won Croatia’s election on Sunday and is set to become the country’s first female president. With more than 99 percent of the ballots counted, Ms. Grabar-Kitarovic, 46, won 50.4 percent of the votes, compared with 49.6 percent for President Ivo Josipovic, the center-left incumbent, the electoral commission said. The election took place in a climate of deep pessimism about Croatia’s economy. The newest member of the European Union, Croatia has one of the weakest economies in the bloc, with an unemployme