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<?php

/**
 * TinyMCEのスタイルをカスタマイズ
 */
function custom_mce_before_init( $settings ) {
    $style_formats = [
            [
                'title' => '段落',
                'block' => 'p',
            ],
            [
                'title' => '大見出し',
                'block' => 'h2',
            ],
            [
                'title' => '中見出し',
                'block' => 'h3',
            ],
            [
                'title' => '小見出し',
                'block' => 'h4',
            ],
            [
                'title' => '外部リンクアイコン',
                'selector' => 'a',
                'classes' => '',
            ]
    ];
    $settings['style_formats'] = json_encode( $style_formats );
    return $settings;
}
add_filter( 'tiny_mce_before_init', 'custom_mce_before_init' );