How to use skinning in maf-skins.xml?

Question

I am setting up maf skinning on IOS and android divces. How to use maf-skin.xml to change css?

I have tried with different css. it didn't reflect it on screen.

<?xml version="1.0" encoding="UTF-8" ?>
<adfmf-skins xmlns="http://xmlns.oracle.com/adf/mf/skin">
  <skin id="s1">
    <extends>mobileAlta-v1.6</extends>
    <id>careSkinFamily-v1.2.android</id>
    <family>careSkin</family>
    <style-sheet-name>custom.css</style-sheet-name>
    <version>
      <default>true</default>
      <name>v1</name>
    </version>
  </skin>
  <skin id="s2">
    <extends>mobileAlta-v1.6</extends>
    <id>careSkinFamily-v1.3.android</id>
    <family>careSkin</family>
    <style-sheet-name>custom_v2.css</style-sheet-name>
    <version>
      <name>v2</name>
    </version>
  </skin>
  <skin-addition>
   <skin-id>mobileAlta-v1.6.iPhone Simulator x86_64</skin-id>
   <style-sheet-name>iPhoneSimStylesheet.css</style-sheet-name>
</skin-addition>
<skin-addition>
   <skin-id>mobileAlta-v1.6.iOS</skin-id>
   <style-sheet-name>css/iOSSimStylesheet.css</style-sheet-name>
</skin-addition>
</adfmf-skins>