grey background & removed light button elevation (#216)

Co-authored-by: marcmuschko <marc.muschko@sap.com>

Corona-Warn-App/src/main/res/layout/fragment_risk_details.xml

@@ -109,11 +109,9 @@
 
                 <androidx.constraintlayout.widget.ConstraintLayout
                     android:id="@+id/risk_details_body"
+                    style="@style/greyBodyBackground"
                     android:layout_width="match_parent"
                     android:layout_height="wrap_content"
-                    android:layout_marginTop="@dimen/spacing_large"
-                    android:background="@color/colorGreyLight"
-                    android:padding="@dimen/spacing_normal"
                     app:layout_constraintEnd_toEndOf="parent"
                     app:layout_constraintStart_toStartOf="parent"
                     app:layout_constraintTop_toBottomOf="@id/risk_details_behavior_wrapper">

Corona-Warn-App/src/main/res/values/styles.xml

@@ -53,6 +53,7 @@
 
     <style name="buttonLight" parent="@style/button">
         <item name="android:backgroundTint">@color/button_light</item>
+        <item name="android:stateListAnimator">@null</item>
     </style>
 
     <style name="buttonIcon">
@@ -133,6 +134,18 @@
     </style>
 
 
+    <!-- ####################################
+            Grey Body Background
+    ###################################### -->
+    <style name="greyBodyBackground">
+        <item name="android:layout_marginTop">@dimen/spacing_large</item>
+        <item name="android:background">@color/colorSurface2</item>
+        <item name="android:paddingStart">@dimen/guideline_start</item>
+        <item name="android:paddingTop">@dimen/spacing_normal</item>
+        <item name="android:paddingEnd">@dimen/guideline_end</item>
+        <item name="android:paddingBottom">@dimen/spacing_normal</item>
+    </style>
+
     <!-- ####################################
                    Text
     ###################################### -->