diff --git a/Userland/Libraries/LibWeb/CSS/GridTrackSize.cpp b/Userland/Libraries/LibWeb/CSS/GridTrackSize.cpp
index 1b389305fc..5d9669a8bc 100644
--- a/Userland/Libraries/LibWeb/CSS/GridTrackSize.cpp
+++ b/Userland/Libraries/LibWeb/CSS/GridTrackSize.cpp
@@ -84,6 +84,13 @@ ExplicitTrackSizing::ExplicitTrackSizing(Vector<CSS::MetaGridTrackSize> meta_gri
 {
 }
 
+ExplicitTrackSizing::ExplicitTrackSizing(Vector<CSS::MetaGridTrackSize> meta_grid_track_sizes, Type type)
+    : m_meta_grid_track_sizes(meta_grid_track_sizes)
+    , m_is_auto_fill(type == Type::AutoFill)
+    , m_is_auto_fit(type == Type::AutoFit)
+{
+}
+
 String ExplicitTrackSizing::to_string() const
 {
     StringBuilder builder;
diff --git a/Userland/Libraries/LibWeb/CSS/GridTrackSize.h b/Userland/Libraries/LibWeb/CSS/GridTrackSize.h
index 4202837469..c813571353 100644
--- a/Userland/Libraries/LibWeb/CSS/GridTrackSize.h
+++ b/Userland/Libraries/LibWeb/CSS/GridTrackSize.h
@@ -87,12 +87,21 @@ private:
 
 class ExplicitTrackSizing {
 public:
+    enum class Type {
+        AutoFit,
+        AutoFill,
+    };
+
     ExplicitTrackSizing();
     ExplicitTrackSizing(Vector<CSS::MetaGridTrackSize>);
     ExplicitTrackSizing(Vector<CSS::MetaGridTrackSize>, int repeat_count);
+    ExplicitTrackSizing(Vector<CSS::MetaGridTrackSize>, Type);
+
     static ExplicitTrackSizing make_auto() { return ExplicitTrackSizing(); };
 
     bool is_repeat() const { return m_is_repeat; }
+    bool is_auto_fill() const { return m_is_auto_fill; }
+    bool is_auto_fit() const { return m_is_auto_fit; }
     int repeat_count() const { return m_repeat_count; }
 
     Vector<CSS::MetaGridTrackSize> meta_grid_track_sizes() const& { return m_meta_grid_track_sizes; }
@@ -106,6 +115,8 @@ public:
 private:
     Vector<CSS::MetaGridTrackSize> m_meta_grid_track_sizes;
     bool m_is_repeat { false };
+    bool m_is_auto_fill { false };
+    bool m_is_auto_fit { false };
     int m_repeat_count { 0 };
 };
 
diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
index e5cc384cba..67f7266e67 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
@@ -5440,6 +5440,8 @@ RefPtr<StyleValue> Parser::parse_grid_track_sizes(Vector<ComponentValue> const&
             // The generic form of the repeat() syntax is, approximately,
             // repeat( [ <integer [1,∞]> | auto-fill | auto-fit ] , <track-list> )
             if (function_token.name().equals_ignoring_case("repeat"sv)) {
+                auto is_auto_fill = false;
+                auto is_auto_fit = false;
                 auto function_tokens = TokenStream(function_token.values());
                 auto comma_separated_list = parse_a_comma_separated_list_of_component_values(function_tokens);
                 if (comma_separated_list.size() != 2)
@@ -5454,6 +5456,10 @@ RefPtr<StyleValue> Parser::parse_grid_track_sizes(Vector<ComponentValue> const&
                 auto repeat_count = 0;
                 if (current_token.is(Token::Type::Number) && current_token.number().is_integer() && current_token.number_value() > 0)
                     repeat_count = current_token.number_value();
+                else if (current_token.is(Token::Type::Ident) && current_token.ident().equals_ignoring_case("auto-fill"sv))
+                    is_auto_fill = true;
+                else if (current_token.is(Token::Type::Ident) && current_token.ident().equals_ignoring_case("auto-fit"sv))
+                    is_auto_fit = true;
 
                 // The second argument is a track list, which is repeated that number of times.
                 TokenStream part_two_tokens { comma_separated_list[1] };
@@ -5478,6 +5484,9 @@ RefPtr<StyleValue> Parser::parse_grid_track_sizes(Vector<ComponentValue> const&
                         auto grid_track_size = parse_grid_track_size(current_component_value);
                         if (!grid_track_size.has_value())
                             return GridTrackSizeStyleValue::create({});
+                        // Automatic repetitions (auto-fill or auto-fit) cannot be combined with intrinsic or flexible sizes.
+                        if (grid_track_size.value().is_flexible_length() && (is_auto_fill || is_auto_fit))
+                            return GridTrackSizeStyleValue::create({});
                         repeat_params.append(grid_track_size.value());
                     }
                     part_two_tokens.skip_whitespace();
@@ -5485,8 +5494,6 @@ RefPtr<StyleValue> Parser::parse_grid_track_sizes(Vector<ComponentValue> const&
                         break;
                 }
 
-                // Automatic repetitions (auto-fill or auto-fit) cannot be combined with intrinsic or flexible sizes.
-
                 // Thus the precise syntax of the repeat() notation has several forms:
                 // <track-repeat> = repeat( [ <integer [1,∞]> ] , [ <line-names>? <track-size> ]+ <line-names>? )
                 // <auto-repeat>  = repeat( [ auto-fill | auto-fit ] , [ <line-names>? <fixed-size> ]+ <line-names>? )
@@ -5506,6 +5513,10 @@ RefPtr<StyleValue> Parser::parse_grid_track_sizes(Vector<ComponentValue> const&
                 // If a repeat() function that is not a <name-repeat> ends up placing two <line-names> adjacent to
                 // each other, the name lists are merged. For example, repeat(2, [a] 1fr [b]) is equivalent to [a]
                 // 1fr [b a] 1fr [b].
+                if (is_auto_fill)
+                    return GridTrackSizeStyleValue::create(CSS::ExplicitTrackSizing(repeat_params, CSS::ExplicitTrackSizing::Type::AutoFill));
+                if (is_auto_fit)
+                    return GridTrackSizeStyleValue::create(CSS::ExplicitTrackSizing(repeat_params, CSS::ExplicitTrackSizing::Type::AutoFit));
                 return GridTrackSizeStyleValue::create(CSS::ExplicitTrackSizing(repeat_params, repeat_count));
             } else {
                 // FIXME: Implement MinMax, etc.