Add a WordPress editor "Styles" drop down with top and bottom margin options

gistfile1.php

<?php

// Enable styles dropdown
add_filter('mce_buttons_2', function ($buttons) {
	array_unshift($buttons, 'styleselect');
	return $buttons;
});

// Register editor "Styles" drop down classes
add_filter('tiny_mce_before_init', function($styles) {
	$classed = array();

	$sides = array(
		'bottom',
		'top',
		'ends',
	);

	foreach ($sides as $side)
	{
		for ($i = 1; $i <= 4; $i++)
		{
			$classes[] = array(
				'title' => "Margin {$side} x{$i}",
				'block' => 'span',
				'classes' => "margin-{$side}-x{$i} margin-class-applied",
				'wrapper' => true,
			);
		}
	}

	$styles['style_formats'] = json_encode($classes);

	return $styles;
});