Using Bootstrap within WordPress admin – a hack by Rush Frisby

Building my first plugin to WordPress I came across Rush Frisby’s Bootstrap hack, so that you can work with Bootstrap within the admin panel, without conflicting with the WordPress admin core styles. You’ll find it here: https://rushfrisby.com/using-bootstrap-in-wordpress-admin-panel/

I have implemented it in my plugin the way he explained.
You can review my code online at https://github.com/kennnielsen/wordpress_dev

There is just one problem with this part:

.bootstrap-wrapper {
    @import (less) url('bootstrap.min.css');
}

The error below will disappear if I remove the (less) from above code, but then the hack is not working as expected – the bootstrap is not loaded within the bootstrap-wrapper.

First of all, I have never really worked with LESS, but I know the basic idea of LESS and how it can ease the work with your CSS.

Nevertheless, when running my plugin, and going to Settings – Custom Login I see the following error:

I have no idea what to do. I have searched the web for answers, but I can’t really find a solution nor a fix for this.

Does anyone have an idea on how to solve this?
– and a brief explanation about .map files?

Thank you all in advance!

For you guys that don’t want to go to Github, see below code used for the admin page.

<?php 

// Meaning of abbreviations:
// clsc = Custom login shortcode

// Runs when plugin is activated
register_activation_hook( PLUGIN_MAIN_FILE, 'clsc_install');
// Create new database fields
function clsc_install() {
    $clsc_options = array(

        'Login_link'        => 'log-in/',
        'Login_string'      => 'Log in',
        'Login_class'       => '', // Default is empty to inherit theme styles
        'Logout_link'       => wp_logout_url( home_url()),
        'Logout_string'     => 'Log out',
        'Logout_class'      => '', // Default is empty to inherit theme styles
        'Account_link'      => 'my-account/',
        'Account_string'    => 'My Account',
        'Account_class'     => '' // Default is empty to inherit theme styles

    );
    add_option('clsc_options_array', $clsc_options, '', 'yes');
}

// Register settings for wordpress to handle all values
function admin_init_register_setting()
{    
    register_setting('wp_plugin_template-group', 'clsc_options_array');

}
add_action('admin_init','admin_init_register_setting');


// Create admin option page
function add_clsc_option_page() {
    add_options_page(
        'Custom Login',             // The text to be displayed in the title tag
        'Custom Login',             // The text to be used for the menu
        'administrator',            // The capability required to display this menu
        'custom-login-shortcodes',  // The unique slug name to refer to this menu
        'clsc_html_page');          // The function to output the page content
}
/* Call the html code */
add_action('admin_menu', 'add_clsc_option_page');

// Enqueue admin styles and scripts
function clsc_enqueue_scripts() {
    global $wpdb;
    $screen = get_current_screen();

    if ( $screen->id != 'settings_page_custom-login-shortcodes' ) {
        return; // exit if incorrect screen id
    } 

        wp_enqueue_style( 'custom-shortcodes-styles', plugins_url( 'admin/css/admin_styles.css', dirname(__FILE__) ) );
        wp_enqueue_style( 'bootstrap', plugins_url('admin/css/bootstrap.css', dirname(__FILE__) ) );
        wp_enqueue_script('admin_js_bootstrap_hack', plugins_url('admin/scripts/bootstrap-hack.js', dirname(__FILE__) ) );
        wp_enqueue_script('jquery', plugins_url('admin/scripts/jquery.min.js', dirname(__FILE__) ) );

}
add_action('admin_enqueue_scripts', 'clsc_enqueue_scripts' );

function clsc_html_page()
{
    if(!current_user_can('manage_options'))
    {
        wp_die( __('You do not have sufficient permissions to access this page.','clsc') );
    }

    ?>

    <script type="text/javascript">

        var default_logout = <?php echo json_encode( wp_logout_url( home_url()) ); ?>;

        $(document).ready(function(){
            $("#logout-default").click(function(){
                $("#logout-field").val(default_logout);
            });
        });
    </script>

    <div class="wrap">

        <form method="post" action="options.php"> 
            <?php 

            $options = get_option('clsc_options_array');     
            settings_fields('wp_plugin_template-group');
            do_settings_fields('wp_plugin_template-group'); 

            ?>          
            <div class="bootstrap-wrapper">
                <div class="row">
                    <div class="col-md-12">
                        <h1><?php _e('Custom Login Shortcode','clsc'); ?></h1>
                        <p><?php _e('To use for shortcode:','clsc'); ?><br/><span class="shortcode-preview">[custom_login]</span></p>
                    </div>
                </div>
                <div class="row" id="login-content">
                    <div class="col-md-4">
                        <h5><?php _e('Log in link:','clsc'); ?></h5>
                        <input name="clsc_options_array[Login_link]" placeholder="<?php _e('Example: log-in/', 'clsc') ?>" class="form-control" type="text" value="<?php echo $options['Login_link']; ?>" />
                    </div>
                    <div class="col-md-4">
                        <h5><?php _e('Log in string:','clsc'); ?></h5>
                        <input name="clsc_options_array[Login_string]" placeholder="<?php _e('Example: Log in', 'clsc') ?>" class="form-control" type="text" value="<?php echo $options['Login_string']; ?>" />
                    </div>
                    <div class="col-md-4">
                        <h5><?php _e('Log in class:','clsc'); ?></h5>
                        <input name="clsc_options_array[Login_class]"  placeholder="<?php _e('Example: login_style', 'clsc') ?>" class="form-control" type="text" value="<?php echo $options['Login_class']; ?>" />
                    </div>
                </div>
                <div class="row top-buffer" id="logout-content">
                    <div class="col-md-4">
                        <h5><?php _e('Log out link:','clsc'); ?></h5>
                        <input id="logout-field" name="clsc_options_array[Logout_link]" placeholder="<?php _e('Example: log-out/', 'clsc') ?>" class="form-control" type="text" value="<?php echo $options['Logout_link']; ?>" />
                        <input class="btn btn-default btn-xs" type="button" name="logout-default" id="logout-default" value="<?php _e('Use default logout link','clsc') ?>"/>
                    </div>
                    <div class="col-md-4">
                        <h5><?php _e('Log out string:','clsc'); ?></h5>
                        <input name="clsc_options_array[Logout_string]" placeholder="<?php _e('Example: Log out', 'clsc') ?>" class="form-control" type="text" value="<?php echo $options['Logout_string']; ?>" />
                    </div>
                    <div class="col-md-4">
                        <h5><?php _e('Log out class:','clsc'); ?></h5>
                        <input name="clsc_options_array[Logout_class]" placeholder="<?php _e('Example: logout_style', 'clsc') ?>" class="form-control" type="text" value="<?php echo $options['Logout_class']; ?>" />
                    </div>
                </div>
                <div class="row top-buffer" id="account-content">
                    <div class="col-md-4">
                        <h5><?php _e('Account link:','clsc'); ?></h5>
                        <input name="clsc_options_array[Account_link]" placeholder="<?php _e('Example: my-account/', 'clsc') ?>" class="form-control" type="text" value="<?php echo $options['Account_link']; ?>" />
                    </div>
                    <div class="col-md-4">
                        <h5><?php _e('Account string:','clsc'); ?></h5>
                        <input name="clsc_options_array[Account_string]" placeholder="<?php _e('Example: My Account', 'clsc') ?>" class="form-control" type="text" value="<?php echo $options['Account_string']; ?>" />
                    </div>
                    <div class="col-md-4">
                        <h5><?php _e('Account class:','clsc'); ?></h5>
                        <input name="clsc_options_array[Account_class]" placeholder="<?php _e('Example: account_style', 'clsc') ?>" class="form-control" type="text" value="<?php echo $options['Account_class']; ?>" />
                    </div>
                </div>            
            </div>

            <?php submit_button( __('Save Changes', 'clsc') ); ?>

        </form>

    </div>

    <?php
}
?>