Fix toot postion on big screen navigatin with j / k

**Is your feature request related to a problem? Please describe.**
On Desktop next toot changes up and down navigating with the keyboard shortcuts

**Describe the solution you'd like**
Next toot selected is either at the top or at the same vertical height

**Describe alternatives you've considered**
Top seems easy, but the center of the screen would be great.

**Additional context**
https://github.com/cheeaun/phanpy/issues/246#issuecomment-1916259706

Thanks for this amazing client.