[Bugfix] message banner hierarchy and rewards card size on smaller sc…

…reens (#803)

* Fix message banner heirarchy bug and rewards card size on smaller screens

* Reading the width from the collection view's bounds

Kickstarter-iOS/Views/Controllers/MessageBannerViewController.swift

@@ -98,6 +98,8 @@ final class MessageBannerViewController: UIViewController, NibLoading {
     let hiddenConstant = self.view.frame.height + (self.view.superview?.safeAreaInsets.bottom ?? 0)
 
     if !isHidden {
+      self.view.superview?.bringSubviewToFront(self.view)
+
       self.view.isHidden = isHidden
 
       self.bottomConstraint?.constant = hiddenConstant

Kickstarter-iOS/Views/Controllers/RewardsCollectionViewController.swift

@@ -206,10 +206,12 @@ final class RewardsCollectionViewController: UICollectionViewController {
     let adjustedContentInset = collectionView.adjustedContentInset
 
     let topBottomSectionInsets = sectionInsets.top + sectionInsets.bottom
+    let leftRightSectionInsets = sectionInsets.left + sectionInsets.right
     let topBottomContentInsets = adjustedContentInset.top + adjustedContentInset.bottom
 
     let itemHeight = collectionView.frame.height - topBottomSectionInsets - topBottomContentInsets
-    let itemWidth = CheckoutConstants.RewardCard.Layout.width
+    let widthByBounds = collectionView.bounds.width - leftRightSectionInsets
+    let itemWidth = min(CheckoutConstants.RewardCard.Layout.width, widthByBounds)
 
     return CGSize(width: itemWidth, height: itemHeight)
   }