Spacing Issue

WordPress often adds empty paragraphs and line breaks around shortcodes. You can fix that by adding this to your functions.php file:

/**
 * Fixes empty <p> and <br> tags showing before and after shortcodes in the
 * output content.
 */
function pb_the_content_shortcode_fix($content) {
    $array = array(
        '<p>['    => '[',
        ']</p>'   => ']',
        ']<br />' => ']',
        ']<br>'   => ']'
    );

    return strtr($content, $array);
}
add_filter('the_content', 'pb_the_content_shortcode_fix');

Once you have added that, you can use CSS to achieve the actual amount of spacing you want between accordion items. For example:

.accordion-content {
    margin-bottom: 10px;
}

I know I didn’t ask the question, but this worked perfectly for me. Thank you!