Regression: CSS isolation not applying all styles in Blazor Server .NET 10 #64776
Description
This issue has been moved from a ticket on Developer Community.
[severity:I'm unable to use this version] [regression] [worked-in:vs 20226 18.0.0]
Environment:
Blazor Server Web App
.NET 10.0.100 SDK
Visual Studio 18.0.2 (Community)
EF Core Power Tools latest
SSMS 22
No Azure services involved
Steps to reproduce:
Create a new Blazor Server Web App project in .NET 10.
Copy existing components and CSS files (App.css, MainCss.css, DefaultCss.css, etc.) into wwwroot/lib.
Add <link> references in App.razor (or host page).
Apply a theme class to <body> (e.g., class="Free-0").
Run the app.
Expected behavior:
Global CSS variables (--Main, etc.) defined in MainCss.css should be recognized.
Dropdowns and other styles should apply as they did in earlier Blazor versions.
Actual behavior:
FontAwesome icons load correctly.
Some CSS rules apply (basic styles).
Dropdown styles and theme variables (--Main) show as “not defined” in dev tools.
Isolation seems to block or ignore certain global styles.
Notes:
Worked in previous Blazor versions.
Regression observed after upgrading to .NET 10 templates.
TheProjectName.styles.css loads, but global CSS doesn’t cascade into isolated components.
Possible gap in CSS isolation pipeline.
You need to get AI involved and let all concerns to be listed let AI do the searching and compile a list for you to deal with . This way is too frustrating for the person trying to help you make a better product
here are a few extra issues I have found
formatting is broken
works sometime then not in the same form
wrapping should be on
settings are scattered and search doesn't work
rollback is blocked can't find vs 202 all links kick us to 2026
you need to update AI
the UI messages are confusing
the editor behaves worse than the previous version
Original Comments
Feedback Bot on 12/15/2025, 05:34 AM:
We have directed your feedback to the appropriate engineering team for further evaluation. The team will review the feedback and notify you about the next steps.