Apply template class names to Matador Buttons

matador_template_button_classes.php

<?php // omit opening PHP tag
add_filter( 'matador_template_button_classes', 'mdocs_matador_template_button_classes', 10, 2 );
/**
 * Matador Template Button Classes Example Filter
 *
 * @since 2020-07-12
 *
 * @param string $classes Space-separated string of classes for a button
 * @param string $context Button context, for filtering purposes, either 'primary', 'secondary', or 'tertiary'
 *
 * @return string
 */
function mdocs_matador_template_button_classes( $classes, $context = 'primary' ) {
  $classes .= ' button';
  if ( 'tertiary' === $context ) {
    $classes .= ' button-tertiary'; 
  } elseif ( 'secondary' === $context ) {
    $classes .= ' button-secondary';
  } elseif ( 'primary' === $context ) {
    $classes .= ' button-primary' );
  }
  
  return $classes;
}