We identified a significant CLS issue affecting users on Facebook's in-app browser (Android). Your page loads Bootstrap from an external CDN, which arrives ~2 seconds after your own stylesheets. During that window, Bootstrap sets .navbar-fixed-top to position: fixed, pulling the navbar out of the document flow and shifting all page content - before your site CSS corrects it back to position: relative. This causes CLS scores 8–15x worse than in standard browsers (p75 CLS ~1.06 vs ~0.15). Fix: add this inline style in before any external tags: This is applied on first render, before any external CSS loads, permanently preventing the shift. No visual change — this is already your intended behavior. Expected result: p75 CLS for Facebook WebView drops from ~1.06 to ~0.25.