#2014: Fix CSS warning in the gui

[laim2003]

This PR fixes #2014

Implemented changes:

• fixed center.css using wrong attribute (fx-font-style instead of fx-font-family)

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Testing instructions

1. Run AppLauncher class
2. No Warning WARNUNG: CSS Error parsing jar:file:/C:/Users/lfaber/projects/IDEasy/conf/mvn/repository/com/devonfw/tools/IDEasy/ide-gui/2026.05.001/ide-gui-2026.05.001.jar!/com/devonfw/ide/gui/style/center.css: Expected '<font-style>' while parsing '-fx-font-style' at [4,18] should be displayed.

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Checklist for this PR

Make sure everything is checked before merging this PR. For further info please also see
our DoD.

• When running mvn clean test locally all tests pass and build is successful
• PR title is of the form #«issue-id»: «brief summary» (e.g. #921: fixed setup.bat). If no issue ID exists, title only.
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  with internal
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[coveralls]

Coverage Report for CI Build 27561444063

Coverage increased (+0.02%) to 71.161%

Details

• Coverage increased (+0.02%) from the base build.
• Patch coverage: No coverable lines changed in this PR.
• 1 coverage regression across 1 file.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

1 previously-covered line in 1 file lost coverage.

File	Lines Losing Coverage	Coverage
com/devonfw/tools/ide/version/VersionSegment.java	1	90.55%

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Coverage Stats

Relevant Lines:	15873
Covered Lines:	11786
Line Coverage:	74.25%
Relevant Branches:	7072
Covered Branches:	4542
Branch Coverage:	64.23%
Branches in Coverage %:	Yes
Coverage Strength:	3.15 hits per line

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💛 - Coveralls

[hohwille]

@laim2003 thanks for the PR. Small fixes improving things are always good and easy to review. Ready for merge.