Democrat Adam Gray captures California's 13th US House District, ousting Republican Rep. John Duarte

[nmmi]

1. 220-215, but 217-215 for the first months...

https://www.msn.com/en-us/news/politics/democrats-win-in-final-uncalled-house-race-locks-in-brutally-small-gop-majority/ar-AA1venpn

Gray's victory means Republicans are set to have 220 seats to Democrats' 215 when the 119th Congress is sworn in on Jan. 3.

To make matters worse for House Republicans, Trump has selected Reps. Michael Waltz (R-Fla.) and Elise Stefanik (R-N.Y.) as his national security advisor and ambassador to the United Nations, respectively.

Both of their seats, along with that of Rep. Matt Gaetz (R-Fla.), who resigned in pursuit of a short-lived nomination for attorney general and said he will not retake his seat in January, won't be filled until the Spring.

While Waltz doesn't plan to resign until Jan. 20, Johnson will still be left with a 217-215 majority for some of the key first months of Trump's term.

and there's this that I don't know enough to comment on:

Republicans only won the House by 7,500 total votes in three congressional districts, Seth Abramson, NYT
https://www.democraticunderground.com/100219787008