Wordpress Query posts - custom posts with different background for each post using count++

mimo_query

<?php 	
			$mimo_query = new WP_Query(
									array(
										'post_type'		=> 'petreceri',
										//'showposts'		=> 8,
										'no_found_rows'	=> true,
									)
								);
	if( $mimo_query->posts ) { ?>
		
		<div class="col_12">
			
				<?php
				// Begin Loop
				$mimo_count=0;
				foreach( $mimo_query->posts as $post ) : setup_postdata( $post );
					$mimo_count++;
					 ?>	
					<div class="col_4 petreceri-<?php echo $mimo_count; ?>">
						<?php the_title(); ?>
					
					</div>
				<?php if( $mimo_count==4 ) { $mimo_count=0; } endforeach; ?>
		</div><!-- /petreceri -->
		
		<?php } wp_reset_postdata(); $mimo_query = NULL; ?>