adapt demos and fix previews

Author: mikhailChelbaev

Examples/DemosApp/DemosApp/ComponentsPreview/PreviewPages/InputFieldPreview.swift

@@ -17,6 +17,7 @@ struct InputFieldPreview: View {
         self.inputField
           .preview
           .onAppear {
+            self.inputField.text = ""
             self.inputField.model = Self.initialModel
           }
           .onChange(of: self.model) { newValue in

Examples/DemosApp/DemosApp/ComponentsPreview/PreviewPages/TextInputPreview.swift

@@ -17,6 +17,7 @@ struct TextInputPreviewPreview: View {
         self.textInput
           .preview
           .onAppear {
+            self.textInput.text = ""
             self.textInput.model = Self.initialModel
           }
           .onChange(of: self.model) { newValue in

Examples/DemosApp/DemosApp/Demos/Login/SwiftUILogin.swift

@@ -62,7 +62,7 @@ struct SwiftUILogin: View {
             ? "Welcome back"
             : "Create an account"
           )
-          .font(.system(size: 30, weight: .bold))
+          .font(UniversalFont.lgHeadline.font)
           .padding(.vertical, 30)
 
           if self.selectedPage == .signUp {
@@ -129,6 +129,7 @@ struct SwiftUILogin: View {
                 model: .init {
                   $0.title = "Continue"
                   $0.isFullWidth = true
+                  $0.color = .primary
                   $0.isEnabled = self.isButtonEnabled
                 },
                 action: {

Examples/DemosApp/DemosApp/Demos/Login/UIKitLogin.swift

@@ -36,7 +36,7 @@ final class UIKitLogin: UIViewController {
   )
   private let titleLabel: UILabel = {
     let label = UILabel()
-    label.font = .systemFont(ofSize: 30, weight: .bold)
+    label.font = UniversalFont.lgHeadline.uiFont
     return label
   }()
   private let nameInput = UKInputField(
@@ -74,6 +74,7 @@ final class UIKitLogin: UIViewController {
     model: .init {
       $0.title = "Continue"
       $0.isFullWidth = true
+      $0.color = .primary
     }
   )
   private let loader = UKLoading()