Refactor intersection observer logic for better performance and accessibility

Author: gavinhon

src/App.jsx

@@ -15,7 +15,10 @@ function App() {
       '(prefers-reduced-motion: reduce)'
     ).matches;
 
-    if (prefersReducedMotion) {
+    if (
+      prefersReducedMotion ||
+      !('IntersectionObserver' in window)
+    ) {
       elements.forEach((element) => element.classList.add('is-visible'));
       return undefined;
     }
@@ -29,7 +32,7 @@ function App() {
           }
         });
       },
-      { threshold: 0.18, rootMargin: '0px 0px -10% 0px' }
+      { threshold: 0.01, rootMargin: '0px 0px -8% 0px' }
     );
 
     elements.forEach((element) => observer.observe(element));