Make download badges lighter to improve contrast (closes #3571)

app/src/main/res/values/colors.xml

@@ -74,6 +74,6 @@
     <color name="md_blue_grey_900">#263238</color>
     <color name="md_blue_grey_800">#37474F</color>
 
-    <color name="pale_green">#99CC99</color>
+    <color name="pale_green">#AAE1AA</color>
 
 </resources>