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Rebase CSS trimmable PR onto latest net11.0 #34010

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c9d5572
Introduce IsCssEnabled feature switch and infer its default value bas…
simonrozsival Dec 15, 2025
6a9b909
Skip loading CSS style sheets when CSS support is trimmed
simonrozsival Dec 15, 2025
41b6edd
Throw in CSS-related APIs when CSS is disabled
simonrozsival Dec 15, 2025
32b68e6
Enable CSS in TestCases.HostApp and add unit tests
simonrozsival Jan 16, 2026
7ded7f1
Improve CSS disabled error messages and add documentation
simonrozsival Jan 16, 2026
dcab283
Initial plan
Copilot Feb 12, 2026
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17 changes: 17 additions & 0 deletions docs/design/FeatureSwitches.md
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Expand Up @@ -6,6 +6,7 @@ The following switches are toggled for applications running on Mono for `TrimMod

| MSBuild Property Name | AppContext Setting | Description |
|-|-|-|
| MauiCssEnabled | Microsoft.Maui.RuntimeFeature.IsCssEnabled | When disabled, CSS stylesheets cannot be used. Defaults to `false` when no `MauiCss` items are present in the project, and `true` otherwise. |
| MauiEnableIVisualAssemblyScanning | Microsoft.Maui.RuntimeFeature.IsIVisualAssemblyScanningEnabled | When enabled, MAUI will scan assemblies for types implementing `IVisual` and for `[assembly: Visual(...)]` attributes and register these types. |
| MauiShellSearchResultsRendererDisplayMemberNameSupported | Microsoft.Maui.RuntimeFeature.IsShellSearchResultsRendererDisplayMemberNameSupported | When disabled, it is necessary to always set `ItemTemplate` of any `SearchHandler`. Displaying search results through `DisplayMemberName` will not work. |
| MauiQueryPropertyAttributeSupport | Microsoft.Maui.RuntimeFeature.IsQueryPropertyAttributeSupported | When disabled, the `[QueryProperty(...)]` attributes won't be used to set values to properties when navigating. |
Expand All @@ -18,6 +19,22 @@ The following switches are toggled for applications running on Mono for `TrimMod
| EnableMauiDiagnostics | Microsoft.Maui.RuntimeFeature.EnableMauiDiagnostics | Enables MAUI specific diagnostics, like VisualDiagnostics and BindingDiagnostics. Defaults to EnableDiagnostics |
| _EnableMauiAspire | Microsoft.Maui.RuntimeFeature.EnableMauiAspire | When enabled, MAUI Aspire integration features are available. **Warning**: Using Aspire outside of Debug configuration may introduce performance and security risks in production. |

## MauiCssEnabled

When this feature is disabled, CSS stylesheets cannot be parsed or applied to UI elements. Any attempt to use CSS will throw a `NotSupportedException`.

**Default behavior**: This feature is automatically disabled when your project has no `MauiCss` items (CSS files). If your project includes any CSS files, the feature is automatically enabled.

**When to enable manually**: If your app loads CSS stylesheets dynamically at runtime (e.g., from a network source or embedded resources) rather than including them as `MauiCss` build items, you need to explicitly enable this feature:

```xml
<PropertyGroup>
<MauiCssEnabled>true</MauiCssEnabled>
</PropertyGroup>
```

**Trimming benefits**: When disabled, the .NET trimmer can eliminate CSS-related code paths, reducing the final application size.

## MauiEnableIVisualAssemblyScanning

When this feature is not enabled, custom and third party `IVisual` types will not be automatically discovered and registered.
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7 changes: 6 additions & 1 deletion ...rols/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets
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Expand Up @@ -303,6 +303,7 @@
<MauiImplicitCastOperatorsUsageViaReflectionSupport Condition="'$(MauiImplicitCastOperatorsUsageViaReflectionSupport)' == ''">false</MauiImplicitCastOperatorsUsageViaReflectionSupport>
<MauiEnableXamlCBindingWithSourceCompilation Condition="'$(MauiEnableXamlCBindingWithSourceCompilation)' == ''">true</MauiEnableXamlCBindingWithSourceCompilation>
<MauiHybridWebViewSupported Condition="'$(MauiHybridWebViewSupported)' == ''">false</MauiHybridWebViewSupported>
<MauiCssEnabled Condition="'$(MauiCssEnabled)' == '' and '@(MauiCss->Count())' == '0'">false</MauiCssEnabled>
<!-- FIXME: https://github.com/xamarin/xamarin-macios/issues/22065 -->
<MobileAggressiveAttributeTrimming Condition="'$(PublishAot)' == 'true' and '$(MobileAggressiveAttributeTrimming)' == ''">false</MobileAggressiveAttributeTrimming>

Expand Down Expand Up @@ -339,10 +340,14 @@
Condition="'$(MauiHybridWebViewSupported)' != ''"
Value="$(MauiHybridWebViewSupported)"
Trim="true" />
<RuntimeHostConfigurationOption Include="Microsoft.Maui.RuntimeFeature.IsCssEnabled"
Condition="'$(MauiCssEnabled)' != ''"
Value="$(MauiCssEnabled)"
Trim="true" />
<RuntimeHostConfigurationOption Include="Microsoft.Maui.RuntimeFeature.AreNamescopesSupported"
Condition="'$(MauiNamescopesSupported)' != ''"
Value="$(MauiNamescopesSupported)"
Trim="true" />
Trim="true" />
<RuntimeHostConfigurationOption Include="Microsoft.Maui.RuntimeFeature.EnableDiagnostics"
Condition="'$(EnableDiagnostics)' != ''"
Value="$(EnableDiagnostics)"
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99 changes: 0 additions & 99 deletions src/Controls/src/Core/Properties/AssemblyInfo.cs
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@@ -1,8 +1,6 @@
using System.Runtime.CompilerServices;
using Microsoft.Maui.Controls;
using Microsoft.Maui.Controls.Internals;
using Microsoft.Maui.Controls.StyleSheets;
using Compatibility = Microsoft.Maui.Controls.Compatibility;

[assembly: InternalsVisibleTo("Microsoft.AspNetCore.Components.WebView.Maui")]

Expand Down Expand Up @@ -83,100 +81,3 @@
[assembly: XmlnsPrefix("http://schemas.microsoft.com/dotnet/2021/maui", "maui")]
[assembly: XmlnsPrefix("http://schemas.microsoft.com/dotnet/2021/maui/design", "d")]
[assembly: XmlnsPrefix("http://schemas.microsoft.com/winfx/2009/xaml", "x")]

[assembly: StyleProperty("background-color", typeof(VisualElement), nameof(VisualElement.BackgroundColorProperty))]
[assembly: StyleProperty("background", typeof(VisualElement), nameof(VisualElement.BackgroundProperty))]
[assembly: StyleProperty("background-image", typeof(Page), nameof(Page.BackgroundImageSourceProperty))]
[assembly: StyleProperty("border-color", typeof(IBorderElement), nameof(BorderElement.BorderColorProperty))]
[assembly: StyleProperty("border-color", typeof(IBorderView), nameof(Border.StrokeProperty))]
[assembly: StyleProperty("border-radius", typeof(ICornerElement), nameof(CornerElement.CornerRadiusProperty))]
[assembly: StyleProperty("border-radius", typeof(Button), nameof(Button.CornerRadiusProperty))]
#pragma warning disable CS0618 // Type or member is obsolete
[assembly: StyleProperty("border-radius", typeof(Frame), nameof(Frame.CornerRadiusProperty))]
#pragma warning restore CS0618 // Type or member is obsolete
[assembly: StyleProperty("border-radius", typeof(IBorderView), nameof(Border.StrokeShapeProperty))]
[assembly: StyleProperty("border-radius", typeof(ImageButton), nameof(BorderElement.CornerRadiusProperty))]
[assembly: StyleProperty("border-width", typeof(IBorderElement), nameof(BorderElement.BorderWidthProperty))]
[assembly: StyleProperty("border-width", typeof(IBorderView), nameof(Border.StrokeThicknessProperty))]
[assembly: StyleProperty("color", typeof(IColorElement), nameof(ColorElement.ColorProperty), Inherited = true)]
[assembly: StyleProperty("color", typeof(ITextElement), nameof(TextElement.TextColorProperty), Inherited = true)]
[assembly: StyleProperty("text-transform", typeof(ITextElement), nameof(TextElement.TextTransformProperty), Inherited = true)]
[assembly: StyleProperty("color", typeof(ProgressBar), nameof(ProgressBar.ProgressColorProperty))]
[assembly: StyleProperty("color", typeof(Switch), nameof(Switch.OnColorProperty))]
[assembly: StyleProperty("column-gap", typeof(Grid), nameof(Grid.ColumnSpacingProperty))]
[assembly: StyleProperty("direction", typeof(VisualElement), nameof(VisualElement.FlowDirectionProperty), Inherited = true)]
[assembly: StyleProperty("font-family", typeof(IFontElement), nameof(FontElement.FontFamilyProperty), Inherited = true)]
[assembly: StyleProperty("font-size", typeof(IFontElement), nameof(FontElement.FontSizeProperty), Inherited = true)]
[assembly: StyleProperty("font-style", typeof(IFontElement), nameof(FontElement.FontAttributesProperty), Inherited = true)]
[assembly: StyleProperty("height", typeof(VisualElement), nameof(VisualElement.HeightRequestProperty))]
[assembly: StyleProperty("margin", typeof(View), nameof(View.MarginProperty))]
[assembly: StyleProperty("margin-left", typeof(View), nameof(View.MarginLeftProperty))]
[assembly: StyleProperty("margin-top", typeof(View), nameof(View.MarginTopProperty))]
[assembly: StyleProperty("margin-right", typeof(View), nameof(View.MarginRightProperty))]
[assembly: StyleProperty("margin-bottom", typeof(View), nameof(View.MarginBottomProperty))]
[assembly: StyleProperty("max-lines", typeof(Label), nameof(Label.MaxLinesProperty))]
[assembly: StyleProperty("min-height", typeof(VisualElement), nameof(VisualElement.MinimumHeightRequestProperty))]
[assembly: StyleProperty("min-width", typeof(VisualElement), nameof(VisualElement.MinimumWidthRequestProperty))]
[assembly: StyleProperty("opacity", typeof(VisualElement), nameof(VisualElement.OpacityProperty))]
[assembly: StyleProperty("padding", typeof(IPaddingElement), nameof(PaddingElement.PaddingProperty))]
[assembly: StyleProperty("padding-left", typeof(IPaddingElement), nameof(PaddingElement.PaddingLeftProperty), PropertyOwnerType = typeof(PaddingElement))]
[assembly: StyleProperty("padding-top", typeof(IPaddingElement), nameof(PaddingElement.PaddingTopProperty), PropertyOwnerType = typeof(PaddingElement))]
[assembly: StyleProperty("padding-right", typeof(IPaddingElement), nameof(PaddingElement.PaddingRightProperty), PropertyOwnerType = typeof(PaddingElement))]
[assembly: StyleProperty("padding-bottom", typeof(IPaddingElement), nameof(PaddingElement.PaddingBottomProperty), PropertyOwnerType = typeof(PaddingElement))]
[assembly: StyleProperty("row-gap", typeof(Grid), nameof(Grid.RowSpacingProperty))]
[assembly: StyleProperty("text-align", typeof(ITextAlignmentElement), nameof(TextAlignmentElement.HorizontalTextAlignmentProperty), Inherited = true)]
[assembly: StyleProperty("text-decoration", typeof(IDecorableTextElement), nameof(DecorableTextElement.TextDecorationsProperty))]
[assembly: StyleProperty("transform", typeof(VisualElement), nameof(VisualElement.TransformProperty))]
[assembly: StyleProperty("transform-origin", typeof(VisualElement), nameof(VisualElement.TransformOriginProperty))]
[assembly: StyleProperty("vertical-align", typeof(ITextAlignmentElement), nameof(TextAlignmentElement.VerticalTextAlignmentProperty))]
[assembly: StyleProperty("visibility", typeof(VisualElement), nameof(VisualElement.IsVisibleProperty), Inherited = true)]
[assembly: StyleProperty("width", typeof(VisualElement), nameof(VisualElement.WidthRequestProperty))]
[assembly: StyleProperty("letter-spacing", typeof(ITextElement), nameof(TextElement.CharacterSpacingProperty), Inherited = true)]
[assembly: StyleProperty("line-height", typeof(Microsoft.Maui.Controls.ILineHeightElement), nameof(LineHeightElement.LineHeightProperty), Inherited = true)]

//flex
[assembly: StyleProperty("align-content", typeof(FlexLayout), nameof(FlexLayout.AlignContentProperty))]
[assembly: StyleProperty("align-items", typeof(FlexLayout), nameof(FlexLayout.AlignItemsProperty))]
[assembly: StyleProperty("align-self", typeof(VisualElement), nameof(FlexLayout.AlignSelfProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("flex-direction", typeof(FlexLayout), nameof(FlexLayout.DirectionProperty))]
[assembly: StyleProperty("flex-basis", typeof(VisualElement), nameof(FlexLayout.BasisProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("flex-grow", typeof(VisualElement), nameof(FlexLayout.GrowProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("flex-shrink", typeof(VisualElement), nameof(FlexLayout.ShrinkProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("flex-wrap", typeof(VisualElement), nameof(FlexLayout.WrapProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("justify-content", typeof(FlexLayout), nameof(FlexLayout.JustifyContentProperty))]
[assembly: StyleProperty("order", typeof(VisualElement), nameof(FlexLayout.OrderProperty), PropertyOwnerType = typeof(FlexLayout))]
[assembly: StyleProperty("position", typeof(FlexLayout), nameof(FlexLayout.PositionProperty))]

//xf specific
[assembly: StyleProperty("-maui-placeholder", typeof(IPlaceholderElement), nameof(PlaceholderElement.PlaceholderProperty))]
[assembly: StyleProperty("-maui-placeholder-color", typeof(IPlaceholderElement), nameof(PlaceholderElement.PlaceholderColorProperty))]
[assembly: StyleProperty("-maui-max-length", typeof(InputView), nameof(InputView.MaxLengthProperty))]
[assembly: StyleProperty("-maui-bar-background-color", typeof(IBarElement), nameof(BarElement.BarBackgroundColorProperty))]
[assembly: StyleProperty("-maui-bar-text-color", typeof(IBarElement), nameof(BarElement.BarTextColorProperty))]
[assembly: StyleProperty("-maui-orientation", typeof(ScrollView), nameof(ScrollView.OrientationProperty))]
[assembly: StyleProperty("-maui-horizontal-scroll-bar-visibility", typeof(ScrollView), nameof(ScrollView.HorizontalScrollBarVisibilityProperty))]
[assembly: StyleProperty("-maui-vertical-scroll-bar-visibility", typeof(ScrollView), nameof(ScrollView.VerticalScrollBarVisibilityProperty))]
[assembly: StyleProperty("-maui-min-track-color", typeof(Slider), nameof(Slider.MinimumTrackColorProperty))]
[assembly: StyleProperty("-maui-max-track-color", typeof(Slider), nameof(Slider.MaximumTrackColorProperty))]
[assembly: StyleProperty("-maui-thumb-color", typeof(Slider), nameof(Slider.ThumbColorProperty))]
[assembly: StyleProperty("-maui-spacing", typeof(StackBase), nameof(StackBase.SpacingProperty))]
[assembly: StyleProperty("-maui-orientation", typeof(StackLayout), nameof(StackLayout.OrientationProperty))]

[assembly: StyleProperty("-maui-visual", typeof(VisualElement), nameof(VisualElement.VisualProperty))]
[assembly: StyleProperty("-maui-vertical-text-alignment", typeof(Label), nameof(TextAlignmentElement.VerticalTextAlignmentProperty))]
[assembly: StyleProperty("-maui-thumb-color", typeof(Switch), nameof(Switch.ThumbColorProperty))]

[assembly: StyleProperty("-maui-shadow", typeof(VisualElement), nameof(VisualElement.ShadowProperty))]

//shell
[assembly: StyleProperty("-maui-flyout-background", typeof(Shell), nameof(Shell.FlyoutBackgroundColorProperty))]
[assembly: StyleProperty("-maui-shell-background", typeof(Element), nameof(Shell.BackgroundColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-disabled", typeof(Element), nameof(Shell.DisabledColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-foreground", typeof(Element), nameof(Shell.ForegroundColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-tabbar-background", typeof(Element), nameof(Shell.TabBarBackgroundColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-tabbar-disabled", typeof(Element), nameof(Shell.TabBarDisabledColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-tabbar-foreground", typeof(Element), nameof(Shell.TabBarForegroundColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-tabbar-title", typeof(Element), nameof(Shell.TabBarTitleColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-tabbar-unselected", typeof(Element), nameof(Shell.TabBarUnselectedColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-title", typeof(Element), nameof(Shell.TitleColorProperty), PropertyOwnerType = typeof(Shell))]
[assembly: StyleProperty("-maui-shell-unselected", typeof(Element), nameof(Shell.UnselectedColorProperty), PropertyOwnerType = typeof(Shell))]
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