diff --git a/ph-css/src/main/java/com/helger/css/decl/CSSSelectorAttribute.java b/ph-css/src/main/java/com/helger/css/decl/CSSSelectorAttribute.java
index f82af397..cae959a2 100644
--- a/ph-css/src/main/java/com/helger/css/decl/CSSSelectorAttribute.java
+++ b/ph-css/src/main/java/com/helger/css/decl/CSSSelectorAttribute.java
@@ -35,6 +35,7 @@
  * A single CSS selector attribute.
  *
  * @see ECSSAttributeOperator
+ * @see ECSSAttributeCase
  * @author Philip Helger
  */
 @NotThreadSafe
@@ -44,6 +45,7 @@ public class CSSSelectorAttribute implements ICSSSelectorMember, ICSSSourceLocat
   private final String m_sAttrName;
   private final ECSSAttributeOperator m_eOperator;
   private final String m_sAttrValue;
+  private final ECSSAttributeCase m_eAttrCase;
   private CSSSourceLocation m_aSourceLocation;
 
   private static boolean _isValidNamespacePrefix (@Nullable final String sNamespacePrefix)
@@ -61,12 +63,22 @@ public CSSSelectorAttribute (@Nullable final String sNamespacePrefix, @Nonnull @
     m_sAttrName = sAttrName;
     m_eOperator = null;
     m_sAttrValue = null;
+    m_eAttrCase = null;
   }
 
   public CSSSelectorAttribute (@Nullable final String sNamespacePrefix,
                                @Nonnull @Nonempty final String sAttrName,
                                @Nonnull final ECSSAttributeOperator eOperator,
                                @Nonnull final String sAttrValue)
+  {
+    this (sNamespacePrefix, sAttrName, eOperator, sAttrValue, null);
+  }
+
+  public CSSSelectorAttribute (@Nullable final String sNamespacePrefix,
+                               @Nonnull @Nonempty final String sAttrName,
+                               @Nullable final ECSSAttributeOperator eOperator,
+                               @Nullable final String sAttrValue,
+                               @Nullable final ECSSAttributeCase eCaseFlag)
   {
     if (!_isValidNamespacePrefix (sNamespacePrefix))
       throw new IllegalArgumentException ("namespacePrefix is illegal!");
@@ -78,6 +90,7 @@ public CSSSelectorAttribute (@Nullable final String sNamespacePrefix,
     m_sAttrName = sAttrName;
     m_eOperator = eOperator;
     m_sAttrValue = sAttrValue;
+    m_eAttrCase = eCaseFlag;
   }
 
   @Nullable
@@ -105,6 +118,12 @@ public String getAttrValue ()
     return m_sAttrValue;
   }
 
+  @Nullable
+  public ECSSAttributeCase getCaseSensitivityFlag ()
+  {
+    return m_eAttrCase;
+  }
+
   @Nonnull
   @Nonempty
   public String getAsCSSString (@Nonnull final ICSSWriterSettings aSettings, @Nonnegative final int nIndentLevel)
@@ -115,7 +134,11 @@ public String getAsCSSString (@Nonnull final ICSSWriterSettings aSettings, @Nonn
       aSB.append (m_sNamespacePrefix);
     aSB.append (m_sAttrName);
     if (m_eOperator != null)
+    {
       aSB.append (m_eOperator.getAsCSSString (aSettings, nIndentLevel)).append (m_sAttrValue);
+      if (m_eAttrCase != null)
+        aSB.append (' ').append (m_eAttrCase.getName ());
+    }
     return aSB.append (']').toString ();
   }
 
@@ -141,7 +164,8 @@ public boolean equals (final Object o)
     return EqualsHelper.equals (m_sNamespacePrefix, rhs.m_sNamespacePrefix) &&
            m_sAttrName.equals (rhs.m_sAttrName) &&
            EqualsHelper.equals (m_eOperator, rhs.m_eOperator) &&
-           EqualsHelper.equals (m_sAttrValue, rhs.m_sAttrValue);
+           EqualsHelper.equals (m_sAttrValue, rhs.m_sAttrValue) &&
+           EqualsHelper.equals (m_eAttrCase, rhs.m_eAttrCase);
   }
 
   @Override
@@ -151,6 +175,7 @@ public int hashCode ()
                                        .append (m_sAttrName)
                                        .append (m_eOperator)
                                        .append (m_sAttrValue)
+                                       .append (m_eAttrCase)
                                        .getHashCode ();
   }
 
@@ -161,6 +186,7 @@ public String toString ()
                                        .append ("attrName", m_sAttrName)
                                        .appendIfNotNull ("operator", m_eOperator)
                                        .appendIfNotNull ("attrValue", m_sAttrValue)
+                                       .appendIfNotNull ("caseFlag", m_eAttrCase)
                                        .appendIfNotNull ("SourceLocation", m_aSourceLocation)
                                        .getToString ();
   }
diff --git a/ph-css/src/main/java/com/helger/css/decl/ECSSAttributeCase.java b/ph-css/src/main/java/com/helger/css/decl/ECSSAttributeCase.java
new file mode 100644
index 00000000..a9620155
--- /dev/null
+++ b/ph-css/src/main/java/com/helger/css/decl/ECSSAttributeCase.java
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2014-2025 Philip Helger (www.helger.com)
+ * philip[at]helger[dot]com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.helger.css.decl;
+
+import com.helger.annotation.Nonempty;
+import com.helger.annotation.Nonnegative;
+import com.helger.base.lang.EnumHelper;
+import com.helger.base.name.IHasName;
+import com.helger.css.ICSSWriteable;
+import com.helger.css.ICSSWriterSettings;
+
+import jakarta.annotation.Nonnull;
+import jakarta.annotation.Nullable;
+
+/**
+ * Enumeration with case sensitivity flags as in
+ * <code>[foo="bar" i]</code> or <code>[foo="bar" s]</code>
+ *
+ * @author Aditi Singh
+ */
+
+public enum ECSSAttributeCase implements ICSSWriteable, IHasName {
+  CASE_SENSITIVE("s"),
+  CASE_INSENSITIVE("i");
+
+  private final String m_sName;
+
+  ECSSAttributeCase(@Nonnull @Nonempty final String sName) {
+    m_sName = sName;
+  }
+
+  @Nonnull
+  @Nonempty
+  public String getName() {
+    return m_sName;
+  }
+
+  @Nonnull
+  @Nonempty
+  public String getAsCSSString(@Nonnull final ICSSWriterSettings aSettings, @Nonnegative final int nIndentLevel) {
+    return m_sName;
+  }
+
+  @Nullable
+  public static ECSSAttributeCase getFromNameOrNull(@Nullable final String sName) {
+    return EnumHelper.getFromNameOrNull(ECSSAttributeCase.class, sName);
+  }
+}
diff --git a/ph-css/src/main/java/com/helger/css/handler/CSSNodeToDomainObject.java b/ph-css/src/main/java/com/helger/css/handler/CSSNodeToDomainObject.java
index f09301fe..3d9a008e 100644
--- a/ph-css/src/main/java/com/helger/css/handler/CSSNodeToDomainObject.java
+++ b/ph-css/src/main/java/com/helger/css/handler/CSSNodeToDomainObject.java
@@ -166,13 +166,17 @@ private CSSSelectorAttribute _createSelectorAttribute (@Nonnull final CSSNode aN
     }
     else
     {
-      final int nExpectedChildCount = nOperatorIndex + 2;
-      if (nChildren != nExpectedChildCount)
+      // With operator and value
+      int nMin = nOperatorIndex + 2;
+      // With operator, value and case sensitivity flag
+      int nMax = nOperatorIndex + 3;
+      
+      if (nChildren < nMin || nChildren > nMax)
         _throwUnexpectedChildrenCount (aNode,
                                        "Illegal number of children present (" +
                                               nChildren +
-                                              ") - expected " +
-                                              nExpectedChildCount);
+                                              ") - expected it to be more than " +
+                                              nMin + " and less than " + nMax);
 
       // With operator...
       final CSSNode aOperator = aNode.jjtGetChild (nOperatorIndex);
@@ -182,10 +186,20 @@ private CSSSelectorAttribute _createSelectorAttribute (@Nonnull final CSSNode aN
       final CSSNode aAttrValue = aNode.jjtGetChild (nOperatorIndex + 1);
       _expectNodeType (aAttrValue, ECSSNodeType.ATTRIBVALUE);
 
+      ECSSAttributeCase eCaseFlag = null;
+      // Optional case sensitivity flag
+      if (nChildren == nMax)
+      {
+        final CSSNode aFlag = aNode.jjtGetChild (nOperatorIndex + 2);
+        _expectNodeType (aFlag, ECSSNodeType.ATTRIBCASE);
+        eCaseFlag = ECSSAttributeCase.getFromNameOrNull (aFlag.getText ());
+      }
+
       ret = new CSSSelectorAttribute (sNamespacePrefix,
                                       sAttrName,
                                       ECSSAttributeOperator.getFromNameOrNull (aOperator.getText ()),
-                                      aAttrValue.getText ());
+                                      aAttrValue.getText (),
+                                      eCaseFlag);
     }
     if (m_bUseSourceLocation)
       ret.setSourceLocation (aNode.getSourceLocation ());
diff --git a/ph-css/src/main/java/com/helger/css/handler/ECSSNodeType.java b/ph-css/src/main/java/com/helger/css/handler/ECSSNodeType.java
index 1a213391..bda7c1a5 100644
--- a/ph-css/src/main/java/com/helger/css/handler/ECSSNodeType.java
+++ b/ph-css/src/main/java/com/helger/css/handler/ECSSNodeType.java
@@ -68,6 +68,7 @@ public enum ECSSNodeType
   ATTRIB (ParserCSS30TreeConstants.JJTATTRIBUTESELECTOR),
   ATTRIBOPERATOR (ParserCSS30TreeConstants.JJTATTRIBOPERATOR),
   ATTRIBVALUE (ParserCSS30TreeConstants.JJTATTRIBVALUE),
+  ATTRIBCASE (ParserCSS30TreeConstants.JJTATTRIBCASE),
   // RELATIVE_SELECTOR (ParserCSS30TreeConstants.JJTRELATIVESELECTOR),
   SELECTORCOMBINATOR (ParserCSS30TreeConstants.JJTSELECTORCOMBINATOR),
   NTH (ParserCSS30TreeConstants.JJTNTH),
diff --git a/ph-css/src/main/jjtree/ParserCSS30.jjt b/ph-css/src/main/jjtree/ParserCSS30.jjt
index e9608f3c..6b2117fb 100644
--- a/ph-css/src/main/jjtree/ParserCSS30.jjt
+++ b/ph-css/src/main/jjtree/ParserCSS30.jjt
@@ -942,6 +942,21 @@ void attribValue() :
   )
 }
 
+void attribCase() : {}
+{
+  ( <S> )*
+  ( <IDENT>
+    {
+      final String v = token.image;
+      if ("i".equalsIgnoreCase(v) || "s".equalsIgnoreCase(v))
+        jjtThis.setText(v.toLowerCase(java.util.Locale.ROOT));
+      else
+        throw new ParseException("Invalid case-sensitivity flag '" + v +
+                                  "'. Only 'i' or 's' are allowed.");
+    }
+  )?
+}
+
 void attributeSelector() : {}
 {
   <LSQUARE>
@@ -957,7 +972,9 @@ void attributeSelector() : {}
     ( <S> )*
     attribValue()
     ( <S> )*
+    attribCase()
   )?
+  ( <S> )*  
   <RSQUARE>
 }
 
diff --git a/ph-css/src/test/java/com/helger/css/decl/CSSStyleRuleTest.java b/ph-css/src/test/java/com/helger/css/decl/CSSStyleRuleTest.java
index eb65baef..f7baae90 100644
--- a/ph-css/src/test/java/com/helger/css/decl/CSSStyleRuleTest.java
+++ b/ph-css/src/test/java/com/helger/css/decl/CSSStyleRuleTest.java
@@ -74,7 +74,7 @@ public void testRead1 ()
   @Test
   public void testRead2 ()
   {
-    CSSStyleRule aSR = _parse ("div, .colored, #my-red, #menu > .active, a[href^=red] { }");
+    CSSStyleRule aSR = _parse ("div, .colored, #my-red, #menu > .active, a[href^=red i] { }");
     assertEquals (5, aSR.getSelectorCount ());
 
     assertEquals (1, aSR.getSelectorAtIndex (0).getMemberCount ());
@@ -94,6 +94,7 @@ public void testRead2 ()
     assertEquals (2, aSR.getSelectorAtIndex (4).getMemberCount ());
     assertTrue (aSR.getSelectorAtIndex (4).getMemberAtIndex (0) instanceof CSSSelectorSimpleMember);
     assertTrue (aSR.getSelectorAtIndex (4).getMemberAtIndex (1) instanceof CSSSelectorAttribute);
+    assertEquals (ECSSAttributeCase.CASE_INSENSITIVE, ((CSSSelectorAttribute) aSR.getSelectorAtIndex (4).getMemberAtIndex (1)).getCaseSensitivityFlag ());
 
     // Create the same rule by application
     final CSSStyleRule aCreated = new CSSStyleRule ();
@@ -107,7 +108,8 @@ public void testRead2 ()
                                             .addMember (new CSSSelectorAttribute (null,
                                                                                   "href",
                                                                                   ECSSAttributeOperator.BEGINMATCH,
-                                                                                  "red")));
+                                                                                  "red",
+                                                                                  ECSSAttributeCase.CASE_INSENSITIVE)));
     TestHelper.testDefaultImplementationWithEqualContentObject (aSR, aCreated);
   }
 }