title: Flutter container stuck to size
body: <p>I am developing an app that is a grid of wordpress articles.
  My problem is this: I want each container to be longer than wider but cannot change from a square.</p>
  
  <p>I also get the following error:</p>
  
  <pre><code>flutter: ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY
  ╞═════════════════════════════════════════════════════════
  flutter: The following message was thrown during layout:
  flutter: A RenderFlex overflowed by 5.9 pixels on the bottom.
  flutter:
  flutter: The overflowing RenderFlex has an orientation of Axis.vertical.
  flutter: The edge of the RenderFlex that is overflowing has been marked in the rendering with a yellow and
  flutter: black striped pattern. This is usually caused by the contents being too big for the RenderFlex.
  flutter: Consider applying a flex factor (e.g. using an Expanded widget) to force the children of the
  flutter: RenderFlex to fit within the available space instead of being sized to their natural size.
  flutter: This is considered an error condition because it indicates that there is content that cannot be
  flutter: seen. If the content is legitimately bigger than the available space, consider clipping it with a
  flutter: ClipRect widget before putting it in the flex, or using a scrollable container rather than a Flex,
  flutter: like a ListView.
  flutter: The specific RenderFlex in question is:
  flutter:   RenderFlex#b5cf8 OVERFLOWING
  flutter:   creator: Column ← DecoratedBox ← Padding ← Container ← RepaintBoundary-[&lt;0&gt;] ←
  flutter:   NotificationListener&lt;KeepAliveNotification&gt; ← KeepAlive ← AutomaticKeepAlive ← SliverGrid ←
  flutter:   MediaQuery ← SliverPadding ← Viewport ← ⋯
  flutter:   parentData: &lt;none&gt; (can use size)
  flutter:   constraints: BoxConstraints(w=177.5, h=177.5)
  flutter:   size: Size(177.5, 177.5)
  flutter:   direction: vertical
  flutter:   mainAxisAlignment: start
  flutter:   mainAxisSize: max
  flutter:   crossAxisAlignment: center
  flutter:   verticalDirection: down
  flutter:   ◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤◢◤
  flutter: ════════════════════════════════════════════════════════════════════════════════════════════════════
  flutter: Another exception was thrown: A RenderFlex overflowed by 5.9 pixels on the bottom.
  flutter: Another exception was thrown: A RenderFlex overflowed by 5.9 pixels on the bottom.
  flutter: Another exception was thrown: A RenderFlex overflowed by 5.9 pixels on the bottom.
  flutter: Another exception was thrown: A RenderFlex overflowed by 5.9 pixels on the bottom.
  </code></pre>
  
  <p>Any Ideas?</p>