fix: remove empty :global selector that breaks Lightning CSS

[martijnrusschen]

Summary

• Moved the sr-only comment from above the .react-datepicker__sr-only selector to inside it
• This prevents Sass from generating an empty :global {} block in the CSS modules output when compiling datepicker-cssmodules.scss
• Fixes build failures when using Rolldown Vite with Lightning CSS minification, which throws "SyntaxError: Invalid empty selector"

Root Cause

When the /* sr-only utility class for accessibility */ comment was placed as a standalone comment before the .react-datepicker__sr-only class, Sass would wrap it in its own :global {} block in the CSS modules output:

:global {
  /* sr-only utility class for accessibility */
}

Since a comment doesn't count as actual CSS content, this resulted in an empty selector block that Lightning CSS rejects.

Test plan

• Verified yarn build completes successfully
• Verified no empty :global {} blocks in generated CSS modules files
• All 1448 tests pass

Fixes #5989

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.26%. Comparing base (be38873) to head (6b82ecc).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6165   +/-   ##
=======================================
  Coverage   99.26%   99.26%           
=======================================
  Files          30       30           
  Lines        3792     3792           
  Branches     1631     1648   +17     
=======================================
  Hits         3764     3764           
  Misses         27       27           
  Partials        1        1           

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