Merge pull request #301 from GetStream/fix/buttonsize

fix(ui): fix button size

packages/stream_chat_flutter/lib/src/back_button.dart

@@ -21,12 +21,12 @@ class StreamBackButton extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return Stack(
+      alignment: Alignment.center,
       children: [
-        Padding(
-          padding: const EdgeInsets.all(14.0),
-          child: RawMaterialButton(
-            shape:
-                RoundedRectangleBorder(borderRadius: BorderRadius.circular(4)),
+        RawMaterialButton(
+          shape: RoundedRectangleBorder(
+            borderRadius: BorderRadius.circular(4),
+          ),
           elevation: 0,
           highlightElevation: 0,
           focusElevation: 0,
@@ -39,12 +39,12 @@ class StreamBackButton extends StatelessWidget {
               Navigator.maybePop(context);
             }
           },
+          padding: const EdgeInsets.all(14.0),
           child: StreamSvgIcon.left(
             size: 24,
             color: StreamChatTheme.of(context).colorTheme.black,
           ),
         ),
-        ),
         if (showUnreads)
           Positioned(
             top: 7,