fixed arrow alignment

[Craig-Rosario]

Closes #10134

Align/Fix the navigation arrows, positioning them on the sides of the covers for better usability.

Technical

Testing

1. Go to the add-cover section of a book (eg. https://openlibrary.org/works/OL69166W/Italian_journeys/add-cover)

Screenshot

Before:

After:

Stakeholders

@mekarpeles

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 17.44%. Comparing base (347bff9) to head (a936ff1).
Report is 168 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #10169      +/-   ##
==========================================
+ Coverage   17.12%   17.44%   +0.31%     
==========================================
  Files          89       89              
  Lines        4752     4792      +40     
  Branches      831      848      +17     
==========================================
+ Hits          814      836      +22     
- Misses       3428     3436       +8     
- Partials      510      520      +10     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.