Summary

Fixes https://wordpress.org/support/topic/no-photos-showing-since-update-2-0/

When a theme has customized their style.php template so that it does not include the manual inclusion of amp-default.css, the result is changes to that stylesheet will not be included. So if someone has a Gallery block that is showing as a slideshow, it won't render properly if this CSS from amp-default.css is not added to the page:

If the theme does not intentionally include amp-default.css like so:

Then they won't get such rules.

We can avoid this from happening in the future by printing amp-default.css via the amp_post_template_css action, rather than manually printing it in the style.php.

This workaround code also does the trick:

add_action( 'amp_post_template_css', function () {
	echo file_get_contents( AMP__DIR__ . '/assets/css/amp-default.css' ); // phpcs:ignore WordPress.WP.AlternativeFunctions
} );

Checklist

• My pull request is addressing an open issue (please create one otherwise).
• My code is tested and passes existing tests.
• My code follows the Engineering Guidelines (updates are often made to the guidelines, check it out periodically).