diff --git a/src/client/features/Member/template.tsx b/src/client/features/Member/template.tsx
index 7874fb1e46c..acebb843187 100644
--- a/src/client/features/Member/template.tsx
+++ b/src/client/features/Member/template.tsx
@@ -142,7 +142,9 @@ export const MemberPage: React.FC<MemberPageProps> = props => {
             <InfoItemLabel>
               <Translation text="birthday" />
             </InfoItemLabel>
-            <InfoItemValue>{formatDate(birthday)}</InfoItemValue>
+            <InfoItemValue>
+              <time dateTime={birthday}>{formatDate(birthday)}</time>
+            </InfoItemValue>
             <InfoItemLabel>
               <Translation text="height" />
             </InfoItemLabel>
diff --git a/src/client/store/app/context.tsx b/src/client/store/app/context.tsx
index 389cae3b90f..e4f398cc2e2 100644
--- a/src/client/store/app/context.tsx
+++ b/src/client/store/app/context.tsx
@@ -18,9 +18,7 @@ type Context = {
 };
 
 export const Context = React.createContext<Context>({
-  themeMode: 'auto',
-  themeKey: 'light',
-  language: 'ja',
+  ...getInitialState(),
   setThemeKey: () => null,
   setTheme: () => null,
   setLanguage: () => null,
diff --git a/src/client/store/app/reducer.ts b/src/client/store/app/reducer.ts
index fb8ba4f1d63..9f878346e15 100644
--- a/src/client/store/app/reducer.ts
+++ b/src/client/store/app/reducer.ts
@@ -8,13 +8,10 @@ type State = {
   language: Language;
 };
 
-export const getInitialState = (
-  theme?: ThemeMode | null,
-  language?: Language | null
-): State => ({
-  themeMode: theme ?? 'auto',
-  themeKey: theme === 'dark' ? 'dark' : 'light',
-  language: language ?? 'ja',
+export const getInitialState = (): State => ({
+  themeMode: 'auto',
+  themeKey: 'dark',
+  language: 'ja',
 });
 
 type Action =