FontAwesome

<?php

/**

 * [fa] shortcode

 * Usage: [fa icon="envelope" style="solid" size="48" class="my-extra-class" label="Email"]

 * - icon: Font Awesome icon name without the "fa-" prefix (e.g., "envelope", "facebook")

 * - style: solid | regular | brands (default: solid)  [light is Pro-only; we fall back]

 * - size: number in px (e.g., 20, 48) OR FA keyword (sm, lg, xl, 2x, 3x...) (default: inherit)

 * - class: optional extra classes

 * - label: accessible label; when set, we render role="img" + aria-label

 */

add_shortcode('fa', function ($atts) {

    $atts = shortcode_atts([

        'icon'  => 'circle',

        'style' => 'solid',

        'size'  => '',

        'class' => '',

        'label' => '',

        'title' => '',

    ], $atts, 'fa');

    // Map requested style to FA 6 Free class

    $style = strtolower(trim($atts['style']));

    switch ($style) {

        case 'brands':

        case 'brand':

            $style_class = 'fa-brands';

            break;

        case 'regular': // Regular is partially free

            $style_class = 'fa-regular';

            break;

        case 'light':   // Light is Pro; fall back to solid

            $style_class = 'fa-solid';

            break;

        case 'solid':

        default:

            $style_class = 'fa-solid';

            break;

    }

    // Build size (px or FA keyword)

    $size = trim($atts['size']);

    $style_attr = '';

    $size_class = '';

    if ($size !== '') {

        if (is_numeric($size)) {

            // Numeric = pixels

            $style_attr = ' style="font-size:' . intval($size) . 'px"';

        } else {

            // Assume FA keyword like 'xl', '2x', etc.

            $size_class = ' fa-' . preg_replace('/[^a-z0-9x\-]/i', '', $size);

        }

    }

    $icon = preg_replace('/[^a-z0-9\-]/i', '', $atts['icon']); // simple sanitize

    $extra = trim($atts['class']);

    $title = esc_attr($atts['title']);

    // Accessibility

    $label = trim($atts['label']);

    $role  = $label !== '' ? ' role="img" aria-label="' . esc_attr($label) . '"' : ' aria-hidden="true"';

    return '<i class="' . esc_attr($style_class . ' fa-' . $icon . $size_class . ($extra ? ' ' . $extra : '')) . '"' . $role . ($title ? ' title="'.$title.'"' : '') . $style_attr . '></i>';

});