I'm glad you asked, because I'm going to see if I can work it out.
Labour and the Tories are going to win 220 each. So that's 440.
And the Lib Dems, SNP and others all added up say 80 - ish. Probably more, but 80 for approx.
So that's 520 seats.
Of those 130 the Tories need 100+
But Labour only needs 20+ to keep them out
And here's the kick.
The more centrist the Tories position themselves to win those 100 marginals, the more the Brexit party munches into them over at the far right
They're still going to be the biggest party. They are certainly going to beat Labour by maybe up to a hundred seats. But they still can't win the election.
They can't win majorities since. The trouble with the Tories is they still think they're a landslide government, and they're not.