Fix Color properties widgets setting

[ptsavol]

Add stylesheet to link and jump properties to make scroll area bg transparent.

Fixes #3012

Checklist before merging

• Unit tests pass

[codecov]

Codecov Report

Attention: Patch coverage is 76.92308% with 3 lines in your changes missing coverage. Please review.

Project coverage is 67.16%. Comparing base (e318e36) to head (82c6b8a).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
spinetoolbox/widgets/properties_widget.py	25.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3021      +/-   ##
==========================================
+ Coverage   67.15%   67.16%   +0.01%     
==========================================
  Files         193      193              
  Lines       37061    37066       +5     
  Branches     4445     4445              
==========================================
+ Hits        24887    24895       +8     
+ Misses      10918    10915       -3     
  Partials     1256     1256              

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