diff --git a/baselines/dom.generated.d.ts b/baselines/dom.generated.d.ts
index d0debd766..ccd5a41d6 100644
--- a/baselines/dom.generated.d.ts
+++ b/baselines/dom.generated.d.ts
@@ -2743,24 +2743,24 @@ interface CSSStyleDeclaration {
     gap: string;
     glyphOrientationHorizontal: string | null;
     glyphOrientationVertical: string;
-    grid: string | null;
-    gridArea: string | null;
-    gridAutoColumns: string | null;
-    gridAutoFlow: string | null;
-    gridAutoRows: string | null;
-    gridColumn: string | null;
-    gridColumnEnd: string | null;
+    grid: string;
+    gridArea: string;
+    gridAutoColumns: string;
+    gridAutoFlow: string;
+    gridAutoRows: string;
+    gridColumn: string;
+    gridColumnEnd: string;
     gridColumnGap: string;
-    gridColumnStart: string | null;
+    gridColumnStart: string;
     gridGap: string;
-    gridRow: string | null;
-    gridRowEnd: string | null;
+    gridRow: string;
+    gridRowEnd: string;
     gridRowGap: string;
-    gridRowStart: string | null;
-    gridTemplate: string | null;
-    gridTemplateAreas: string | null;
-    gridTemplateColumns: string | null;
-    gridTemplateRows: string | null;
+    gridRowStart: string;
+    gridTemplate: string;
+    gridTemplateAreas: string;
+    gridTemplateColumns: string;
+    gridTemplateRows: string;
     height: string | null;
     hyphens: string;
     imageOrientation: string;
diff --git a/inputfiles/idl/CSS Grid Layout.widl b/inputfiles/idl/CSS Grid Layout.widl
new file mode 100644
index 000000000..144577040
--- /dev/null
+++ b/inputfiles/idl/CSS Grid Layout.widl	
@@ -0,0 +1,17 @@
+partial interface CSSStyleDeclaration {
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridTemplateColumns;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridTemplateRows;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridTemplateAreas;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridTemplate;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridAutoColumns;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridAutoRows;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridAutoFlow;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString grid;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridRowStart;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridColumnStart;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridRowEnd;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridColumnEnd;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridRow;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridColumn;
+  [CEReactions] attribute [TreatNullAs=EmptyString] CSSOMString gridArea;
+};
diff --git a/inputfiles/idlSources.json b/inputfiles/idlSources.json
index 713061c9d..d721c9b8d 100644
--- a/inputfiles/idlSources.json
+++ b/inputfiles/idlSources.json
@@ -28,6 +28,10 @@
         "url": "https://www.w3.org/TR/css-fonts-3/",
         "title": "CSS Fonts"
     },
+    {
+        "url": "https://www.w3.org/TR/css-grid-1/",
+        "title": "CSS Grid Layout"
+    },
     {
         "url": "https://drafts.csswg.org/css-images-3/",
         "title": "CSS Images"