I'm pretty confused by the New York Times' page describing the Senate results (https://www.nytimes.com/interactive/2018/11/06/us/elections/results-senate-elections.html).
It says that the Democrats lost two seats and the GOP gained two seats. But the current (pre-election) Senate composition was 51 Republicans and 49 Democrats. How can the Republicans gain 2 seats and still be at 51? And if the Democrats lost 2 seats why are they at 46 in that page, instead of 47?
Is it some weird accounting due to the fact that not every race has been called?