fixed fade

src/contents/Home.tsx

 import React, { useEffect, useRef } from "react";
 
 export function Home() {
-  {/* debug */}
-  const [ isVisible ] = React.useState();
+  const [isVisible, setVisible] = React.useState(false);
   const domRef = useRef(null)!;
   useEffect(() => {
     const observer = new IntersectionObserver(entries => {
+      entries.forEach(entry => setVisible(entry.isIntersecting));
+      {/* debug */}
       entries.forEach(entry => console.log(entry.isIntersecting));
     });
     observer.observe(domRef.current!);