-----------Ouvrez sidebar.php

--Remplacez ca :
		<!-- Start Categories -->
		<div class="widget widget_categories">
			<h2>Categories</h2>
			<?= sidebar_list_categories() ?>
		</div>
		<!-- End Categories -->

--Par ca :
		<!-- Start Categories -->
		<div class="widget widget_categories">
			<h2>Les Categories X</h2>
			<ul class="columns">
				<?php
					//sidebar_list_categories();
					$categories = the_categories('sites');
					$nb = mysql_num_rows($categories);
					$i = 0;
					while ($category = mysql_fetch_assoc($categories)) {
						if($i==ceil($nb/2)) echo '</ul><ul class="columns">';
						$categories_name = stripslashes($category['name']); 
						$categories_url = $category['slug'];
				?>
				<li><a href="<?= siteinfo('url') . '/' . siteinfo('sitesurl') . '/' . $categories_url . '/' ?>" title="Voir tous les sites de la categorie &quot;<?= htmlspecialchars($categories_name); ?>&quot;"><?= htmlspecialchars($categories_name) ?></a></li>
				<?php
						$i++;
					}
				?>
			</ul>
		</div>
		<!-- End Categories -->


-----------Ouvrez style.css

--Remplacez ca :

/* SideBar +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
#sidebar { margin-left:680px; padding:0 0 10px; width:300px; }
#sidebar .widget { padding: 0 10px 10px; margin-bottom: 20px;}
#sidebar .widget p { margin-top: 0px; }
#sidebar .widget h2 { font-size: 14px; font-weight: bold; padding: 0px 0px 1px 0px; margin: 0px; color:#114477; }
#sidebar .widget ul { margin:5px 0 0 20px; padding: 0px;}
#sidebar .widget li { margin: 0px; padding: 0 0 0 5px; list-style-type: square; }
#sidebar .widget a { color:#114477;}
#sidebar .widget a:visited { color:#114477;}
#sidebar .widget a:hover { color:#ccc; text-decoration: none;}

#sidebar .widget_categories { margin: 0px;}

--Par ca :

/* SideBar +++++++++++++++++++++++++++++++++++ */
#sidebar { width: 300px; float: right; position: relative; padding: 0px; }
/* SideBar +++++++++++++++++++++++++++++++++++ */
#sidebar .widget { width: 300px; float: left; padding: 0 10px 10px; margin-bottom: 10px;}
#sidebar .widget p { margin-top: 0px; }
#sidebar .widget h2 { font-size: 18px; letter-spacing: -1px; font-weight: bold; padding: 0px 0px 1px 0px; margin: 0px; color:#408bc1; border-bottom:1px solid #408bc1; }
#sidebar .widget ul { margin: 0px; padding: 0px;}
#sidebar .widget ul.columns { margin: 0px; padding: 0px; float: left; width: 147px; }
#sidebar .widget ul.columns a { color:#000; font-size: 14px; }
#sidebar .widget ul.columns a:link, #sidebar .widget ul.columns a:visited { text-decoration: underline; }
#sidebar .widget ul.columns a:hover, #sidebar .widget ul.columns a:active { text-decoration: none; }
#sidebar .widget li { margin: 0px; padding: 0px; list-style-type: none; }
#sidebar .widget a, #sidebar .widget a:visited { color:#000; text-decoration: underline; }
#sidebar .widget a:hover { text-decoration: none;}

#sidebar .widget_categories { margin: 0px;}