How do I apply custom css styles only to Amp pages

I have a wordpress website which I am coverting to an AMP website for now I am using the amp plugin Now my website has a lot of css files and the style that I can inline is limited so I am trying to add a custom css using :

<style amp-custom>
 .someclass={/*my custom css I want it to affect only amp pages*/}

</style>

I can add the style without problem to all pages by adding it to the header.php file, Now The thing is I want this tyle to be applied only to my amp pages , they have a special urls (Adding ?amp at the end).

• www.mywebsite.com : is my website

• www.mywebsite.com?amp is the amp page for my website, I am overriding the css by adding these inline custom css to affect these pages.

can I make it so that the custom css is only applied to the amp pages ?

You can use amp_post_template_css action if you are using this plugin.

function custom_post_template_css() {
  ?>
  .someclass={
    /*my custom css I want it to affect only amp pages*/
  }
  <?php
}
add_action( 'amp_post_template_css','custom_post_template_css', 11 );

Please refer to the Custom CSS for the documentation.