From a03fc2b79b4dbd151f3c1201d331d7e347261c13 Mon Sep 17 00:00:00 2001
From: Jason Finch <jason.finch@gmail.com>
Date: Fri, 27 Mar 2026 12:04:48 +1000
Subject: [PATCH] Fix @font-face font-weight range values being lost during
 parse

The font-weight converter only accepted a single keyword or integer,
so range values like "100 700" (valid CSS Fonts Level 4) were silently
dropped. Use WeightIntegerConverter.Many(1, 2) to accept 1-2 space-
separated weight integers.
---
 src/AngleSharp.Css.Tests/Rules/FontFace.cs    | 103 ++++++++++++++++++
 .../Declarations/FontWeightDeclaration.cs     |   3 +-
 2 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/src/AngleSharp.Css.Tests/Rules/FontFace.cs b/src/AngleSharp.Css.Tests/Rules/FontFace.cs
index 6504bfa6..5470fd9b 100644
--- a/src/AngleSharp.Css.Tests/Rules/FontFace.cs
+++ b/src/AngleSharp.Css.Tests/Rules/FontFace.cs
@@ -44,5 +44,108 @@ public void FontFaceOpenSansNoSource()
             Assert.AreEqual("", fontface.Variant);
             Assert.AreEqual("", fontface.Weight);
         }
+
+        [Test]
+        public void FontFaceWeightRangeShouldBePreserved()
+        {
+            var src = "@font-face { font-weight: 100 700; }";
+            var sheet = ParseStyleSheet(src);
+            Assert.IsNotNull(sheet);
+            Assert.AreEqual(1, sheet.Rules.Length);
+            Assert.IsInstanceOf<CssFontFaceRule>(sheet.Rules[0]);
+            var fontface = (ICssFontFaceRule)sheet.Rules[0];
+            Assert.AreEqual("100 700", fontface.Weight);
+        }
+
+        [Test]
+        public void FontFaceSingleWeightIntegerShouldBePreserved()
+        {
+            var src = "@font-face { font-weight: 400; }";
+            var sheet = ParseStyleSheet(src);
+            Assert.IsNotNull(sheet);
+            Assert.AreEqual(1, sheet.Rules.Length);
+            Assert.IsInstanceOf<CssFontFaceRule>(sheet.Rules[0]);
+            var fontface = (ICssFontFaceRule)sheet.Rules[0];
+            Assert.AreEqual("400", fontface.Weight);
+        }
+
+        [Test]
+        public void FontFaceWeightRangeShouldRoundtripViaToCss()
+        {
+            var src = "@font-face { font-weight: 100 700; }";
+            var sheet = ParseStyleSheet(src);
+            var css = sheet.ToCss();
+            Assert.That(css, Does.Contain("font-weight: 100 700"));
+        }
+
+        [Test]
+        public void FontFaceWeightBoldKeywordShouldBePreserved()
+        {
+            var src = "@font-face { font-weight: bold; }";
+            var sheet = ParseStyleSheet(src);
+            Assert.AreEqual(1, sheet.Rules.Length);
+            var fontface = (ICssFontFaceRule)sheet.Rules[0];
+            Assert.AreEqual("bold", fontface.Weight);
+        }
+
+        [Test]
+        public void FontFaceWeightNormalKeywordShouldBePreserved()
+        {
+            var src = "@font-face { font-weight: normal; }";
+            var sheet = ParseStyleSheet(src);
+            Assert.AreEqual(1, sheet.Rules.Length);
+            var fontface = (ICssFontFaceRule)sheet.Rules[0];
+            Assert.AreEqual("normal", fontface.Weight);
+        }
+
+        [Test]
+        public void FontFaceWeightMinBoundary100ShouldBePreserved()
+        {
+            var src = "@font-face { font-weight: 100; }";
+            var sheet = ParseStyleSheet(src);
+            Assert.AreEqual(1, sheet.Rules.Length);
+            var fontface = (ICssFontFaceRule)sheet.Rules[0];
+            Assert.AreEqual("100", fontface.Weight);
+        }
+
+        [Test]
+        public void FontFaceWeightMaxBoundary900ShouldBePreserved()
+        {
+            var src = "@font-face { font-weight: 900; }";
+            var sheet = ParseStyleSheet(src);
+            Assert.AreEqual(1, sheet.Rules.Length);
+            var fontface = (ICssFontFaceRule)sheet.Rules[0];
+            Assert.AreEqual("900", fontface.Weight);
+        }
+
+        [Test]
+        public void FontFaceWeightOutOfRange1ShouldBeInvalid()
+        {
+            var src = "@font-face { font-weight: 1; }";
+            var sheet = ParseStyleSheet(src);
+            Assert.AreEqual(1, sheet.Rules.Length);
+            var fontface = (ICssFontFaceRule)sheet.Rules[0];
+            Assert.AreEqual("", fontface.Weight);
+        }
+
+        [Test]
+        public void FontFaceWeightOutOfRange1000ShouldBeInvalid()
+        {
+            var src = "@font-face { font-weight: 1000; }";
+            var sheet = ParseStyleSheet(src);
+            Assert.AreEqual(1, sheet.Rules.Length);
+            var fontface = (ICssFontFaceRule)sheet.Rules[0];
+            Assert.AreEqual("", fontface.Weight);
+        }
+
+        [Test]
+        public void FontFaceWeightThreeValuesShouldBeInvalid()
+        {
+            var src = "@font-face { font-weight: 100 400 700; }";
+            var sheet = ParseStyleSheet(src);
+            Assert.AreEqual(1, sheet.Rules.Length);
+            var fontface = (ICssFontFaceRule)sheet.Rules[0];
+            Assert.AreEqual("", fontface.Weight);
+        }
     }
 }
diff --git a/src/AngleSharp.Css/Declarations/FontWeightDeclaration.cs b/src/AngleSharp.Css/Declarations/FontWeightDeclaration.cs
index 869b5923..d047027b 100644
--- a/src/AngleSharp.Css/Declarations/FontWeightDeclaration.cs
+++ b/src/AngleSharp.Css/Declarations/FontWeightDeclaration.cs
@@ -1,5 +1,6 @@
 namespace AngleSharp.Css.Declarations
 {
+    using AngleSharp.Css.Converters;
     using AngleSharp.Css.Dom;
     using System;
     using static ValueConverters;
@@ -13,7 +14,7 @@ static class FontWeightDeclaration
             PropertyNames.Font,
         };
 
-        public static IValueConverter Converter = Or(FontWeightConverter, WeightIntegerConverter);
+        public static IValueConverter Converter = Or(FontWeightConverter, WeightIntegerConverter.Many(1, 2));
 
         public static ICssValue InitialValue = InitialValues.FontWeightDecl;