<html lang="ja">
<head>
<meta charset="UTF-8">
<style>
#yuta_thumbnail{
background-size: cover;
background-position: center center;
position: relative;
z-index: 0;
}
#yuta_thumbnail:before{
content: '';
background: inherit;/*背景画像を継承する*/
-webkit-filter: blur(5px);
-moz-filter: blur(5px);
-o-filter: blur(5px);
-ms-filter: blur(5px);
filter: blur(5px);
position: absolute;
top: -5px;
left: -5px;
right: -5px;
bottom: -5px;
z-index: -1;
}
</style>
</head>
<?php
$title_bg = "style=''";
if ( has_post_thumbnail() ) {
$img_url = wp_get_attachment_url( get_post_thumbnail_id() );
$title_bg = "style='background-image:url(".$img_url."); background-repeat: no-repeat; '";
}
?>
<body id="yuta_thumbnail"<?php echo $title_bg; ?>>
<div>
# ここが本文
</div></body>
</html>