Fix Ada sidebar container overflows

[jacbn]

Fixes overflow caused by changes to the Ada sidebar container.

Before (overflows to the right):

After:

---

Also fixes the bad float position on the share link causing certain pages without toptext to appear too small, just by hiding it for non-content pages.

Before:

After:

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 43.53%. Comparing base (439352b) to head (2c2c4ed).

Files with missing lines	Patch %	Lines
src/app/components/elements/PageMetadata.tsx	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2201      +/-   ##
==========================================
- Coverage   43.55%   43.53%   -0.03%     
==========================================
  Files         597      597              
  Lines       25205    25206       +1     
  Branches     7467     8368     +901     
==========================================
- Hits        10979    10974       -5     
- Misses      14177    14183       +6     
  Partials       49       49              

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