Make thumbnails float

I suppose my question is a no-brainer for template design experts, but I’m not one 😉

I’m using a plugin called List Category Posts to list categories in a template defined layout inside pages. It is possible to design your own template, so I’m struggling to modify the default template to list the posts the way I want them to. Basically, all I want to change is to make the thumbnails float left of the excerpt/content text to make space usage more rational. Here is the present code:

//Show category?
if ($cat_link_string != ''){
	$lcp_output = '<p><strong>' . $cat_link_string . '</strong></p>';
}else{
	$lcp_output = '';
}
$lcp_output .= '<ul class="lcp_catlist">';//For default ul
//Posts loop:
foreach($catposts as $single):
	$lcp_output .= '<li><a href="' . get_permalink($single->ID) . '">' . $single->post_title . '</a>';
	//Show comments?
	if($atts['comments'] == yes){
		$lcp_output .= ' (' . $single->comment_count . ')';
	}
	//Style for date:
	if($atts['date']=='yes'){
		$lcp_output .= ' - ' . get_the_time($atts['dateformat'], $single);
	}
	//Show author?
	if($atts['author']=='yes'){
		$lcp_userdata = get_userdata($single->post_author);
		$lcp_output .=" - ".$lcp_userdata->display_name;
	}
	//Show thumbnail?
	if($atts['thumbnail']=='yes'){
		$lcp_output .= '<div class="lcp_thumbnail"><a href="' . get_permalink($single->ID) . '">' . lcp_thumbnail($single) . '</div></a>';
	}
	//Show content?
	if($atts['content']=='yes' && $single->post_content){
		$lcpcontent = apply_filters('the_content', $single->post_content); // added to parse shortcodes
		$lcpcontent = str_replace(']]>', ']]&gt', $lcpcontent); // added to parse shortcodes
		$lcp_output .= '<p>' . $lcpcontent . '</p>'; // line tweaked to output filtered content
	}
	//Show excerpt?
	if($atts['excerpt']=='yes' && !($atts['content']=='yes' && $single->post_content) ){
		$lcp_output .= lcp_excerpt($single);
	}
	$lcp_output .='</li><hr>';
endforeach;
$lcp_output .= '</ul>';

I have successfully added the link to thumbnails, but I can’t resolve the harder part with the thumbnail float. I suppose I have to add the float:left somewhere but everything I’ve tried produces errors or simply displays a float:left text string. So, my question is – where and how exactly should I add this in order to get the thumbnail to float left of the textual content?