diff --git a/src/components/sidebarTableOfContents/index.tsx b/src/components/sidebarTableOfContents/index.tsx
index 774a686c19c1a7..319066c07c94dc 100644
--- a/src/components/sidebarTableOfContents/index.tsx
+++ b/src/components/sidebarTableOfContents/index.tsx
@@ -115,7 +115,8 @@ export function SidebarTableOfContents() {
     // account for the header height
     const rootMarginTop = 100;
     // element is consiered in view if it is in the top 1/3 of the screen
-    const rootMarginBottom = (2 / 3) * window.innerHeight - rootMarginTop;
+    const rootMarginBottomRaw = (2 / 3) * window.innerHeight - rootMarginTop;
+    const rootMarginBottom = Math.floor(rootMarginBottomRaw);
     const observerOptions = {
       rootMargin: `${rootMarginTop}px 0px -${rootMarginBottom}px 0px`,
       threshold: 1,