fix: custom property is not a browserhack

[bartveneman]

No description provided.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.03%. Comparing base (2e3b881) to head (55a6d1e).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #91   +/-   ##
=======================================
  Coverage   95.02%   95.03%           
=======================================
  Files          15       15           
  Lines        2433     2435    +2     
  Branches      629      629           
=======================================
+ Hits         2312     2314    +2     
  Misses        121      121           

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[codecov-commenter]

Bundle Report

Changes will increase total bundle size by 153 bytes (0.12%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
@projectwallace/css-parser-esm	131.1kB	153 bytes (0.12%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: @projectwallace/css-parser-esm

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
parse-*.js	153 bytes	6.71kB	2.33%

Files in parse-*.js:

• ./src/parse-declaration.ts → Total Size: 6.07kB