Weird method of adding CSS in a php file (using <<<CSS and CSS;)? -

i don't understand what's purpose of <<<csss , css;s in following code:

$css_var =  <<<css /*techozoic {$tech['ver']}*/  /*variable styles*/ #page{ background:{$tech_content_bg_color} url({$tech['content_bg_image']}) {$tech_content_bg_repeat} top left; } #header{ background-color:{$tech_content_bg_color}; } body{ font-family:{$tech['default_font']}, sans-serif; font-size: {$tech['body_font_size']}px; background:{$tech_bg_color} url({$tech['bg_image']}) {$tech_bg_repeat} top left; } .techozoic_font_size{ font-size: {$tech['body_font_size']}px; } .narrowcolumn .entry,.widecolumn .entry, .top { font-family:{$tech['body_font']}, sans-serif; } {$tech_post_bg_color_classes}{ background-color:{$tech_post_bg_color}; border-top:1px {$tech_acc_color} solid; } .top{ border:none; } h1{ font-family:{$tech_h1_font}, sans-serif; } h2{ font-family:{$tech_h2_font}, sans-serif; } h3{ font-family:{$tech_h3_font}, sans-serif; } h4{ font-family:{$tech_h4_font}, sans-serif; } h5{ font-family:{$tech_h5_font}, sans-serif; } .blog_title{ font-family:{$tech_blog_title_font}, sans-serif; } .post_title{ font-family:{$tech_post_title_font}, sans-serif; } .sidebar h2, .sidebar h3, #footer h2{ font-family:{$tech_sidebar_font}, sans-serif; } .blog_title{ font-size: {$tech['main_heading_font_size']}em; } .post_title { font-size: {$tech['post_heading_font_size']}em; } .widgettitle { font-size: {$tech['side_heading_font_size']}em; margin: 1px 0; } .sidebar h3 { font-size: {$tech_sidebar_h3_font_size}em; } #content { font-size: {$tech['post_text_font_size']}em; } acronym,abbr,span.caps,small,.trackback li,#commentform input,#commentform textarea,.sidebar { font-size: {$tech['small_font_size']}em; } .description, ul#nav a, ul#admin a, #dropdown li.current_page_item a:hover, .menu li.current-menu-item a:hover, #dropdown li.current_page_item ul a, .menu li.current-menu-item ul a, ul#nav li.current_page_item a:hover,.blog_title a,.blog_title a:visited, #nav2 a, #nav2 li.current_page_item a:hover,#subnav a, #subnav a:visited, #dropdown a, #navmenu .menu li a, #navmenu .menu li.current-menu-item a{ color: {$tech_acc_color}; } .author,#searchform #s, #searchsubmit:hover,#catsubmit:hover,#wp-submit:hover,.postform,#tb_ajaxcontent { background-color: {$tech_acc_color} ; } ul#nav li,ul#admin li, #nav2 li, ul#dropdown li, #navmenu .menu li{ background-color: {$tech_nav_bg_color}; } ul#nav li,ul#admin li, #nav2 li, ul#dropdown li a, #navmenu .menu li a{ font-family:{$tech['nav_font']}, sans-serif; font-size:{$tech['nav_text_font_size']}em; } #navmenu .menu ul.sub-menu li{ background-color: {$tech_nav_ul_bg_color}; } css; if($tech_nav_bg_trans != 'on') { $css_var .=  <<<css ul#nav li.current_page_item,#nav2 li.current_page_item,#nav2 li.current_page_parent,ul#nav2 li.current_page_ancestor,#dropdown li.current_page_item, #navmenu .menu li.current-menu-item { background-color: {$tech_acc_color} ; } ul#nav li:hover,#nav2 li:hover, #nav2 li:active, #dropdown li:hover, #navmenu .menu li:hover { background:#efefef; box-shadow:2px -1px 3px rgba(0, 0, 0, 0.3); -moz-box-shadow:2px -1px 3px rgba(0, 0, 0, 0.3); -webkit-box-shadow:2px -1px 3px rgba(0, 0, 0, 0.3); } ul#nav li.current_page_item ,#nav2 li.current_page_item a,#nav2 li.current_page_parent a, #nav2 li.current_page_ancestor a,#dropdown li.current_page_item a, #navmenu .menu li.current-menu-item a{ color:#f7f7f7; } ul#admin li:hover{ background:#efefef; box-shadow:2px 1px 3px rgba(0, 0, 0, 0.3); -moz-box-shadow:2px 1px 3px rgba(0, 0, 0, 0.3); -webkit-box-shadow:2px 1px 3px rgba(0, 0, 0, 0.3); } css; } $css_var .= <<<css .post_date { background-color:{$tech_acc_color}; } .tags { border-bottom:1px {$tech_acc_color} solid; } #content,h2,h2 a,h2 a:visited,h3,h3 a,h3 a:visited,h4,h5{ color:{$tech_text_color}; } a,h2 a:hover,h3 a:hover,.commentdiv a, .commentdiv a:visited,#user_login,#user_pass,.postform,.commentdiv span, #sidenav a:visited { color:{$tech_link_color}; text-decoration:none; } .date_post,#searchform #s { color:{$tech_post_bg_color}; text-decoration:none; } a:hover,.blog_title a:hover { color:{$tech_link_hov_color}; text-decoration:underline; } a:visited{ color:{$tech_visit_link_color}; } ul#nav li.current_page_item a:hover, ul#nav2 li.current_page_item a:hover, ul#nav2 li.current_page_parent a:hover { color:{$tech_acc_color}; } 

it valid code or bad practice?

that valid heredoc syntax.