Added Surface to MaterialTheme

app/src/main/kotlin/com/tutpro/baresip/Theme.kt

@@ -5,7 +5,9 @@ import androidx.activity.ComponentActivity
 import androidx.activity.SystemBarStyle
 import androidx.activity.enableEdgeToEdge
 import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.Surface
 import androidx.compose.material3.darkColorScheme
 import androidx.compose.material3.dynamicDarkColorScheme
 import androidx.compose.material3.dynamicLightColorScheme
@@ -14,6 +16,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
+import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalView
 
@@ -120,5 +123,11 @@ fun AppTheme(
             onDispose {}
         }
 
-    MaterialTheme(colorScheme = colorScheme, content = content)
+    MaterialTheme(colorScheme = colorScheme) {
+        Surface(
+            modifier = Modifier.fillMaxSize(),
+            color = MaterialTheme.colorScheme.background,
+            content = content
+        )
+    }
 }