title: can I set style of my container in theme data?
body: <p>To make a rounded corner in my container, I can do something like this</p>
  <pre><code>Container(
    decoration: BoxDecoration(
      borderRadius: BorderRadius.all(Radius.circular(20))
    ),
    child: ...
  )
  </code></pre>
  <p>but I need to do it over and over again whenever I create a container with a rounded corner. can I set it in my Theme data? I can set my appBar theme in theme data like the code below, but I need something similar but for the container. how to do that?</p>
  <pre><code>final themeData = ThemeData(
    appBarTheme: _appBarTheme,
  );
  
  const AppBarTheme _appBarTheme = const AppBarTheme(
    elevation: 2,
    centerTitle: true,
    color: const Color.fromRGBO(245, 245, 245, 1),
    textTheme: TextTheme(
      // center text style
      headline6: TextStyle(color: Colors.black, fontSize: 16),
      // Side text style
      bodyText2: TextStyle(color: Colors.black),
    ),
  );
  </code></pre>