From 43aece434a75641d98de37c36ed6895948a830d8 Mon Sep 17 00:00:00 2001
From: Mason Simon <86958+masonicboom@users.noreply.github.com>
Date: Mon, 1 Aug 2022 20:15:34 -0700
Subject: [PATCH] Fallback for contentBoxSize

---
 src/hooks/useGridDimensions.ts | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/hooks/useGridDimensions.ts b/src/hooks/useGridDimensions.ts
index 749ba42004..5c70c401a2 100644
--- a/src/hooks/useGridDimensions.ts
+++ b/src/hooks/useGridDimensions.ts
@@ -28,9 +28,17 @@ export function useGridDimensions(): [
     setBlockSize(initialHeight);
 
     const resizeObserver = new ResizeObserver((entries) => {
-      const size = entries[0].contentBoxSize[0];
-      setInlineSize(handleDevicePixelRatio(size.inlineSize));
-      setBlockSize(size.blockSize);
+      const entry = entries[0];
+      if (entry.contentBoxSize) {
+        const size = entry.contentBoxSize[0];
+        setInlineSize(handleDevicePixelRatio(size.inlineSize));
+        setBlockSize(size.blockSize);
+      } else {
+        // Fallback for browsers that don't support contentBoxSize.
+        const rect = entry.contentRect;
+        setInlineSize(handleDevicePixelRatio(rect.width));
+        setBlockSize(rect.height);
+      }
     });
     resizeObserver.observe(gridRef.current!);