Description:
The sidebar's Styles deck does not show different font formattings when "Show previews" is ticked.

Steps to Reproduce:
1. Open Calc
2. Expand the sidebar
3. Go to the Styles deck, Cell styles
4. Make sure "Show previews" is ticked

Actual Results:
Font doesn't change for the various styles.

Expected Results:
fonts are different depending on the style, just like in Writer's paragraph styles.


Reproducible: Always


User Profile Reset: No

Additional Info:
Note that Format > Conditional > Condition does show the style preview (with colours too, which I think is not necessary for the sidebar given that it creates issues depending on light / dark themes).

Versions:

Version: 7.5.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: c130063895c7a733ad121db1bf5fbceac38f6ad5
CPU threads: 8; OS: Linux 5.15; UI render: default; VCL: gtk3
Locale: en-AU (en_AU.UTF-8); UI: en-US
Calc: threaded

Version: 7.5.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: deb7bc82de19ea8e20c767fdf21f9ba4feb5e9f0
CPU threads: 4; OS: Windows 10.0 Build 19045; UI render: Skia/Raster; VCL: win
Locale: en-GB (en_GB); UI: en-GB
Calc: threaded

Version: 6.3.6.2
Build ID: 2196df99b074d8a661f4036fca8fa0cbfa33a497
CPU threads: 8; OS: Linux 5.15; UI render: default; VCL: gtk3; 
Locale: de-DE (en_AU.UTF-8); UI-Language: en-US
Calc: threaded