   override func viewDidLoad() {
     super.viewDidLoad()
 
-    paletteTitle.text = "Material Palette"
+    paletteTitle.text = "Material Palette-based themes"
     paletteTitle.font = titleFont
     paletteTitle.textColor = titleColor
     paletteTitle.translatesAutoresizingMaskIntoConstraints = false

  let titleColor = AppTheme.globalTheme.colorScheme.onSurfaceColor.withAlphaComponent(0.5)
  let titleFont = AppTheme.globalTheme.typographyScheme.button
  private let cellReuseIdentifier = "cell"
  private let colorSchemeCells = [
    (
      mainColor: AppTheme.defaultTheme.colorScheme.primaryColor,
      colorScheme: { return AppTheme.defaultTheme.colorScheme }
    ),
    (
      mainColor: MDCPalette.blue.tint500,
      colorScheme: { return createSchemeWithPalette(MDCPalette.blue) }
    ),
    (
      mainColor: MDCPalette.red.tint500,
      colorScheme: { return createSchemeWithPalette(MDCPalette.red) }
    ),
    (
      mainColor: MDCPalette.green.tint500,
      colorScheme: { return createSchemeWithPalette(MDCPalette.green) }
    ),
    (
      mainColor: MDCPalette.amber.tint500,
      colorScheme: { return createSchemeWithPalette(MDCPalette.amber) }
    ),
    (
      mainColor: MDCPalette.pink.tint500,
      colorScheme: { return createSchemeWithPalette(MDCPalette.pink) }
    ),
    (
      mainColor: MDCPalette.orange.tint500,
      colorScheme: { return createSchemeWithPalette(MDCPalette.orange) }
    )
  ]
  private let cellSize : CGFloat = 33.0
  private let cellSpacing : CGFloat = 8.0



  func collectionView(_ collectionView: UICollectionView,
                      numberOfItemsInSection section: Int) -> Int {
    return colorSchemeConfigurations.count
  }

  func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    let colorScheme = colorSchemeConfigurations[indexPath.item].colorScheme()
    navigationController?.popViewController(animated: true)
    AppTheme.globalTheme = AppTheme(colorScheme: colorScheme,
                                    typographyScheme: AppTheme.globalTheme.typographyScheme)
  }

