fix: remove fixed height on app shell

[denkristoffer]

Pull Request Template

Description

The fixed height on the app shell means the chapter list table doesn't work too well on smaller screens, you can end up with just a single row in the table. This PR removes the set height.

Quick recording showing before and after:

Screen.Recording.2023-06-26.at.15.32.26.mov

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist

• My code follows the style guidelines of this project
• My commits follow the commit standards of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have checked my code and corrected any misspellings