Things i am attempting to do is call different CSS (for background additional factors) in line with the category the publish is. It ought to be super easy, and labored for that pages, however for some reasons it does not want to dedicate yourself groups.

This is actually the code I've:

 <?php
    if( is_page('Turismo a Bra') || is_page_template( 'turismo.php' ) || is_category('Turismo a Bra')  ) 
    {
    ?>
    <link rel="stylesheet" href="<?php bloginfo('template_url')?>/css/turismo-a-bra.css" type="text/css" media="screen" />      
    <?php } elseif ( is_category ('Eventi') || is_page_template( 'eventi.php' ) || is_page_template( 'eventi.php' ) || is_category('Eventi') )
    {
    ?>
    <link rel="stylesheet" href="<?php bloginfo('template_url')?>/css/eventi.css" type="text/css" media="screen" />
    <?php } elseif ( is_category ('Arte e Cultura') || is_page('Arte e Cultura') || is_page_template( 'arte.php' ) || is_category('Arte e Cultura'))
    {
    ?>
    <link rel="stylesheet" href="<?php bloginfo('template_url')?>/css/arte-e-cultura.css" type="text/css" media="screen" />
    <?php } elseif ( is_category ('Enogastronomia')|| is_page('Enogastronomia') ||  is_page_template( 'enogastronomia.php' )  || is_category('Enogastronomia'))
    {
    ?>
    <link rel="stylesheet" href="<?php bloginfo('template_url')?>/css/enogastronomia.css" type="text/css" media="screen" />
    <?php } elseif ( is_category ('Natura')|| is_page('Natura') || is_page_template( 'natura.php' )  || is_category('Natura'))
    {
    ?>
    <link rel="stylesheet" href="<?php bloginfo('template_url')?>/css/natura.css" type="text/css" media="screen" />
    <?php } else {  ?>

    <?php } ?>

When I stated, labored perfectly for that page template and also the actual page, although not for that groups. I m sur it's very easy, can anybody assist me to?

In my opinion you're while using wrong approach to check category:

Based on the wordpress documentation you utilize is_category() for archive pages (WP Function Reference/is category)

To check on current posts you utilize in_category() (WP Function Reference/in category)