prompt/html_email/print_styles action
Developers can easily add styles from their own plugins into the header of the Postmatic email template using this action.
This action fires after the default Postmatic styles in the <head> section of the html email template.
All inlining and conversion to mobile-friendly css and xhtml will be performed by Postmatic.
Pre-formatting your css
Please appropriately target the content area of the Postmatic template by pre-pending your styles with .postmatic-content.
Example
add_action( 'prompt/html_email/print_styles', 'my_prefix_add_postmatic_styles' );
function my_prefix_add_postmatic_styles() {
printf( '.postmatic-content h1 { color: blue; }' );
}