Mouse scroll stopped working, excessive vertical space added

Not sure after which one exactly, but recently after one of these:
```
[2022-10-02T09:19:27+0200] [ALPM] upgraded anki-git (r9640.fe9b0aecf-1 -> r9650.6944210fb-1)
[2022-10-13T19:41:23+0200] [ALPM] upgraded anki-git (r9650.6944210fb-1 -> r9678.f5abd3c6a-1)
[2022-10-16T16:22:39+0200] [ALPM] upgraded anki-git (r9678.f5abd3c6a-1 -> r9680.c22f6022f-1)
[2022-10-21T21:07:34+0200] [ALPM] upgraded anki-git (r9680.c22f6022f-1 -> r9682.b8c294bf4-1)
[2022-10-23T08:00:42+0200] [ALPM] upgraded anki-git (r9682.b8c294bf4-1 -> r9686.22f54c2c0-1)
[2022-10-26T21:23:27+0200] [ALPM] upgraded anki-git (r9686.22f54c2c0-1 -> r9691.ab6877c71-1)
[2022-10-30T12:40:56+0100] [ALPM] upgraded anki-git (r9691.ab6877c71-1 -> r9701.e5c4ccf08-1)
```
1. scrolling with mouse scroll in the main window stopped working.
2. enormous padding/margin has been added between deck lines, which leads to a lot of wasted vertical space.

Start by reproducing the issue in the main window after the listed anki-git upgrades, checking both mouse-wheel scrolling and the spacing between deck lines. Done means mouse scrolling works again and the excessive vertical padding is removed.

Written by the indexing model from the issue text.