Switch to using CSS to avoid o2 script tags from affecting layout

Hide empty p tags and remove margin from second to last element if there is an o2-data script tag.

mu-plugins/blocks/notice/index.php

@@ -49,6 +49,10 @@ function render_callout_as_notice( $attr, $content, $tag ) {
 
 	// Sanitize message content.
 	$content = wp_kses_post( $content );
+	// Temporarily disable o2 processing while formatting content.
+	add_filter( 'o2_process_the_content', '__return_false', 1 );
+	$content = apply_filters( 'the_content', $content );
+	remove_filter( 'o2_process_the_content', '__return_false', 1 );
 
 	// Create a unique placeholder for the content.
 	// Directly processing `$content` with `do_blocks` can lead to buggy layouts on make.wp.org.

mu-plugins/blocks/notice/postcss/style.pcss

@@ -27,11 +27,20 @@
 		align-self: start;
 	}
 
+	& p:empty {
+		display: none;
+	}
+
 	& p:first-child {
 		margin-block-start: 0;
 	}
 
-	& p:last-child {
+	/* o2 adds a data script tag to the notice content on some Make blogs.
+	 * In this case we need to remove bottom margin from the second to last element instead.
+	 */
+
+	& p:last-child,
+	&:has(.o2-data) :nth-last-child(2) {
 		margin-block-end: 0;
 	}