feat(post) add header, fix style

frontend/app/blog/layout.tsx

@@ -6,7 +6,8 @@ function Layout({
     children: React.ReactNode;
 }) {
     return (
-        <div className={ 'flex flex-auto p-7 pl-2 md:pl-7 items-stretch justify-center' }>
+        // <div className={ 'flex flex-auto p-7 pl-2 md:pl-7 items-stretch justify-center' }>
+        <div className={ 'flex flex-auto p-7 pl-2 md:pl-7 w-full justify-center' }>
             { children }
         </div>
     );