Fix background composable

Change-Id: I548612191b0b99620777c3e2ad0ace56b228d27d

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaApp.kt

@@ -66,6 +66,7 @@ import com.google.samples.apps.nowinandroid.core.designsystem.component.NiaTopAp
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon.DrawableResourceIcon
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon.ImageVectorIcon
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.NiaIcons
+import com.google.samples.apps.nowinandroid.core.designsystem.theme.LocalGradientColors
 import com.google.samples.apps.nowinandroid.feature.settings.R as settingsR
 import com.google.samples.apps.nowinandroid.feature.settings.SettingsDialog
 import com.google.samples.apps.nowinandroid.navigation.NiaNavHost
@@ -86,17 +87,26 @@ fun NiaApp(
         windowSizeClass = windowSizeClass
     ),
 ) {
-    val background: @Composable (@Composable () -> Unit) -> Unit =
-        when (appState.currentTopLevelDestination) {
-            TopLevelDestination.FOR_YOU -> {
-                content ->
-                NiaGradientBackground(content = content)
-            }
-            else -> { content -> NiaBackground(content = content) }
-        }
-
-    background {
+    val showGradientBackground = appState.currentTopLevelDestination == TopLevelDestination.FOR_YOU
 
+    NiaBackground {
+        NiaGradientBackground(
+            topColor = if (showGradientBackground) {
+                LocalGradientColors.current.top
+            } else {
+                Color.Unspecified
+            },
+            bottomColor = if (showGradientBackground) {
+                LocalGradientColors.current.bottom
+            } else {
+                Color.Unspecified
+            },
+            containerColor = if (showGradientBackground) {
+                LocalGradientColors.current.container
+            } else {
+                Color.Unspecified
+            },
+        ) {
             val snackbarHostState = remember { SnackbarHostState() }
 
             Scaffold(
@@ -193,6 +203,7 @@ fun NiaApp(
             }
         }
     }
+}
 
 @Composable
 private fun NiaNavRail(