remove calc from box components app content area

[JeffGreiner-eaton]

Fixes #806.

Changes proposed in this Pull Request:

• remove calc from box component

Screenshots / Screen Recording (if applicable)

• iPad

• iPhone

To Test:

• https://blui-react-docs--pr849-fix-blui-5256-drawer-uuizxqif.web.app/components/drawer/playground
• and resize window or toggle the default view port sizes

Any specific feedback you are looking for?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (976ae15) 84.03% compared to head (f5d1af2) 84.03%.
Report is 8 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #849   +/-   ##
=======================================
  Coverage   84.03%   84.03%           
=======================================
  Files          58       58           
  Lines        1234     1234           
  Branches      158      158           
=======================================
  Hits         1037     1037           
  Misses         98       98           
  Partials       99       99           

Flag	Coverage Δ
unittests	84.03% <ø> (ø)

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[github-actions]

Visit the preview URL for this PR (updated for commit f5d1af2):

https://blui-react-docs--pr849-fix-blui-5256-drawer-uuizxqif.web.app

_{(expires Sun, 11 Feb 2024 16:38:31 GMT)}

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