ui: color cleanup

Change-Id: I1d827cf753400e1b36c039df90fac53555a1e5c4
diff --git a/ring-android/app/src/main/res/layout/camerapicker.xml b/ring-android/app/src/main/res/layout/camerapicker.xml
index 3333559..decf767 100644
--- a/ring-android/app/src/main/res/layout/camerapicker.xml
+++ b/ring-android/app/src/main/res/layout/camerapicker.xml
@@ -17,7 +17,7 @@
         android:layout_centerHorizontal="true"
         android:contentDescription="@string/action_call_decline"
         android:padding="16dp"
-        app:backgroundTint="@color/holo_green_dark"
+        app:backgroundTint="@color/green_500"
         app:rippleColor="@android:color/white"
         app:srcCompat="@drawable/baseline_photo_camera_24"
         app:useCompatPadding="true" />
diff --git a/ring-android/app/src/main/res/layout/frag_call.xml b/ring-android/app/src/main/res/layout/frag_call.xml
index cba46e4..a2dfc70 100644
--- a/ring-android/app/src/main/res/layout/frag_call.xml
+++ b/ring-android/app/src/main/res/layout/frag_call.xml
@@ -178,7 +178,7 @@
                     android:contentDescription="@string/action_call_accept"
                     android:onClick="@{() -> presenter.acceptClicked()}"
                     android:visibility="gone"
-                    app:backgroundTint="#4caf50"
+                    app:backgroundTint="@color/green_500"
                     app:elevation="6dp"
                     app:fabSize="normal"
                     app:pressedTranslationZ="12dp"