fix: contributor card state (#430)

Co-authored-by: guoqqqi <72343596+guoqqqi@users.noreply.github.com>
diff --git a/website/src/pages/index.js b/website/src/pages/index.js
index 1ba05e6..4edbfa5 100644
--- a/website/src/pages/index.js
+++ b/website/src/pages/index.js
@@ -259,20 +259,23 @@
 };
 
 const Contributor200Poster = () => {
-  const [display, setDisplay] = useState(true);
+  const [display, setDisplay] = useState(false);
   const [theme, setTheme] = useState('light');
 
   useEffect(() => {
     addEventListener('click', () => {
-      if (localStorage.getItem('theme') !== theme) {
-        setTheme(localStorage.getItem('theme'));
-      };
+      setTheme(localStorage.getItem('theme'));
     });
-  }, [theme]);
-
-  if (!display || (typeof window !== 'undefined' && localStorage.getItem('SHOW_200_CONTRIBUTOR_EVENT_ENTRY'))) {
-    return null;
-  }
+    if (localStorage.getItem("theme")) {
+      setTheme(localStorage.getItem('theme'));
+    };
+    if (window.matchMedia('(prefers-color-scheme: dark)').matches) {
+      setTheme('dark');
+    }
+    if (!localStorage.getItem('SHOW_200_CONTRIBUTOR_EVENT_ENTRY')) {
+      setDisplay(true);
+    };
+  }, []);
 
   const onClose = () => {
     setDisplay(false);
@@ -281,6 +284,10 @@
     }
   };
 
+  if (!display) {
+    return null;
+  }
+
   return (
     <div className="pic-wrapper">
       <button className="pic-wrapper-close" onClick={onClose}>