LibWeb/CSS: Absolutize color KeywordStyleValues

These get computed to an equivalent RGBColorStyleValue.

To support this, we now store the computed color-scheme on the
ComputationContext when computing properties that might contain a color.

This has a nice bonus of correcting the css-accent-color test's result.

Libraries/LibWeb/CSS/StyleComputer.cpp

@@ -799,7 +799,8 @@ void StyleComputer::collect_animation_into(DOM::AbstractElement abstract_element
                 .viewport_rect = viewport_rect(),
                 .font_metrics = font_metrics,
                 .root_font_metrics = m_root_element_font_metrics },
-            .abstract_element = abstract_element
+            .abstract_element = abstract_element,
+            .color_scheme = computed_properties.color_scheme(document().page().preferred_color_scheme(), document().supported_color_schemes()),
         };
 
         // NOTE: This doesn't necessarily return the specified value if we reach into computed_properties but that
@@ -1569,7 +1570,8 @@ void StyleComputer::compute_property_values(ComputedProperties& style, Optional<
             .font_metrics = font_metrics,
             .root_font_metrics = m_root_element_font_metrics,
         },
-        .abstract_element = abstract_element
+        .abstract_element = abstract_element,
+        .color_scheme = style.color_scheme(document().page().preferred_color_scheme(), document().supported_color_schemes())
     };
 
     // NOTE: This doesn't necessarily return the specified value if we have already computed this property but that

Libraries/LibWeb/CSS/StyleValues/ComputationContext.h

@@ -7,6 +7,7 @@
 #pragma once
 
 #include <LibWeb/CSS/Length.h>
+#include <LibWeb/CSS/PreferredColorScheme.h>
 #include <LibWeb/DOM/AbstractElement.h>
 
 namespace Web::CSS {
@@ -14,6 +15,7 @@ namespace Web::CSS {
 struct ComputationContext {
     Length::ResolutionContext length_resolution_context;
     Optional<DOM::AbstractElement> abstract_element {};
+    Optional<PreferredColorScheme> color_scheme {};
 };
 
 }

Libraries/LibWeb/CSS/StyleValues/KeywordStyleValue.cpp

@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <andreas@ladybird.org>
  * Copyright (c) 2021, Tobias Christiansen <tobyase@serenityos.org>
- * Copyright (c) 2021-2025, Sam Atkins <sam@ladybird.org>
+ * Copyright (c) 2021-2026, Sam Atkins <sam@ladybird.org>
  * Copyright (c) 2022-2023, MacDue <macdue@dueutil.tech>
  *
  * SPDX-License-Identifier: BSD-2-Clause
@@ -10,6 +10,8 @@
 #include "KeywordStyleValue.h"
 #include <LibGfx/Palette.h>
 #include <LibWeb/CSS/CSSKeywordValue.h>
+#include <LibWeb/CSS/StyleValues/NumberStyleValue.h>
+#include <LibWeb/CSS/StyleValues/RGBColorStyleValue.h>
 #include <LibWeb/CSS/SystemColor.h>
 #include <LibWeb/DOM/Document.h>
 #include <LibWeb/Layout/Node.h>
@@ -358,6 +360,35 @@ Optional<Color> KeywordStyleValue::to_color(ColorResolutionContext color_resolut
     }
 }
 
+ValueComparingNonnullRefPtr<StyleValue const> KeywordStyleValue::absolutized(ComputationContext const& context) const
+{
+    if (!has_color())
+        return *this;
+
+    // The currentcolor keyword computes to itself.
+    // https://drafts.csswg.org/css-color-4/#resolving-other-colors
+    if (keyword() == Keyword::Currentcolor)
+        return *this;
+
+    ColorResolutionContext color_resolution_context;
+    if (context.abstract_element.has_value()) {
+        color_resolution_context.document = context.abstract_element->document();
+        color_resolution_context.calculation_resolution_context = CalculationResolutionContext::from_computation_context(context);
+        color_resolution_context.color_scheme = context.color_scheme;
+    }
+
+    auto resolved_color = to_color(color_resolution_context);
+    if (!resolved_color.has_value())
+        return *this;
+
+    return RGBColorStyleValue::create(
+        NumberStyleValue::create(resolved_color->red()),
+        NumberStyleValue::create(resolved_color->green()),
+        NumberStyleValue::create(resolved_color->blue()),
+        NumberStyleValue::create(resolved_color->alpha() / 255.0f),
+        ColorSyntax::Legacy);
+}
+
 Vector<Parser::ComponentValue> KeywordStyleValue::tokenize() const
 {
     return { Parser::Token::create_ident(FlyString::from_utf8_without_validation(string_from_keyword(m_keyword).bytes())) };

Libraries/LibWeb/CSS/StyleValues/KeywordStyleValue.h

@@ -1,7 +1,7 @@
 /*
  * Copyright (c) 2018-2020, Andreas Kling <andreas@ladybird.org>
  * Copyright (c) 2021, Tobias Christiansen <tobyase@serenityos.org>
- * Copyright (c) 2021-2025, Sam Atkins <sam@ladybird.org>
+ * Copyright (c) 2021-2026, Sam Atkins <sam@ladybird.org>
  * Copyright (c) 2022-2023, MacDue <macdue@dueutil.tech>
  *
  * SPDX-License-Identifier: BSD-2-Clause
@@ -50,6 +50,7 @@ public:
     static bool is_color(Keyword);
     virtual bool has_color() const override;
     virtual Optional<Color> to_color(ColorResolutionContext) const override;
+    virtual ValueComparingNonnullRefPtr<StyleValue const> absolutized(ComputationContext const&) const override;
     virtual void serialize(StringBuilder&, SerializationMode) const override;
     virtual Vector<Parser::ComponentValue> tokenize() const override;
     virtual GC::Ref<CSSStyleValue> reify(JS::Realm&, FlyString const& associated_property) const override;

Tests/LibWeb/Text/expected/css-accent-color.txt

@@ -1,2 +1,2 @@
 Before bgColor=rgb(105, 105, 105)
-After bgColor=rgb(0, 0, 255)
+After bgColor=rgb(61, 174, 233)