diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
index 6d787eeaef..0a00a88a7b 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
@@ -416,7 +416,12 @@ Result<Selector::SimpleSelector, Parser::SelectorParsingResult> Parser::parse_si
             .type = Selector::SimpleSelector::Type::Attribute,
             .attribute = {
                 .match_type = Selector::SimpleSelector::Attribute::MatchType::HasAttribute,
-                .name = attribute_part.token().ident(),
+                // FIXME: Case-sensitivity is defined by the document language.
+                // HTML is insensitive with attribute names, and our code generally assumes
+                // they are converted to lowercase, so we do that here too. If we want to be
+                // correct with XML later, we'll need to keep the original case and then do
+                // a case-insensitive compare later.
+                .name = attribute_part.token().ident().to_lowercase_string(),
             }
         };
 
diff --git a/Userland/Libraries/LibWeb/CSS/SelectorEngine.cpp b/Userland/Libraries/LibWeb/CSS/SelectorEngine.cpp
index 026dee981b..d614a3d3d4 100644
--- a/Userland/Libraries/LibWeb/CSS/SelectorEngine.cpp
+++ b/Userland/Libraries/LibWeb/CSS/SelectorEngine.cpp
@@ -40,9 +40,11 @@ static bool matches_attribute(CSS::Selector::SimpleSelector::Attribute const& at
     case CSS::Selector::SimpleSelector::Attribute::MatchType::ContainsString:
         return element.attribute(attribute.name).contains(attribute.value);
         break;
-    case CSS::Selector::SimpleSelector::Attribute::MatchType::StartsWithSegment:
-        return element.attribute(attribute.name).split_view('-').first() == attribute.value;
+    case CSS::Selector::SimpleSelector::Attribute::MatchType::StartsWithSegment: {
+        auto segments = element.attribute(attribute.name).split_view('-');
+        return !segments.is_empty() && segments.first() == attribute.value;
         break;
+    }
     case CSS::Selector::SimpleSelector::Attribute::MatchType::StartsWithString:
         return element.attribute(attribute.name).starts_with(attribute.value);
         break;
diff --git a/Userland/Libraries/LibWeb/DOM/Element.h b/Userland/Libraries/LibWeb/DOM/Element.h
index c4b360f84e..3878cc433d 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.h
+++ b/Userland/Libraries/LibWeb/DOM/Element.h
@@ -45,7 +45,7 @@ public:
     // NOTE: This is for the JS bindings
     const FlyString& namespace_uri() const { return namespace_(); }
 
-    bool has_attribute(const FlyString& name) const { return !attribute(name).is_null(); }
+    bool has_attribute(const FlyString& name) const { return find_attribute(name) != nullptr; }
     bool has_attributes() const { return !m_attributes.is_empty(); }
     String attribute(const FlyString& name) const;
     String get_attribute(const FlyString& name) const { return attribute(name); }