Changing the CSS with a plugin

You’re using the wrong hook to enqueue your styles: add_action(‘admin_enqueue_scripts’, ‘seizoenplugin_enqueue_styles’ ); As the name suggests, admin_enqueue_scripts is for enqueuing scripts and styles in the admin. To enqueue scripts on the front end use wp_enqueue_scripts: add_action(‘wp_enqueue_scripts’, ‘seizoenplugin_enqueue_styles’ );

Bootstrap slider not working

You’ve tagged your question correctly with wp_enqueue_script but it doesn’t appear in your code so you are probably missing the jQuery library and bootstrap by the looks of it. Try adding the following: add_action(‘wp_enqueue_scripts’, ‘wp_add_jquery’); function wp_add_jquery () { wp_register_script( ‘my_jquery’, ‘http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js’); // Add your other scripts here (bootstrap, etc.) }