Css yang sy buat kok tidak berpengaruh ke hasil single ya #judul_single

<?php
require_once "core/init.php";
require_once "view/header.php";

$error  = '';
$id     = $_GET['id'];

if(isset($_GET['id'])) {
    $article = tampilkan_per_id($id);
    while($row = mysqli_fetch_assoc($article)){
        $judul_awal     = $row['judul'];
        $konten_awal    = $row['isi'];
        $tag_awal       = $row['tag'];
    }
}
?>

<p id="judul_single">
    <?=$judul_awal; ?>
</p>

<p id="isi_single">
    <?=$konten_awal; ?>
</p>

<p id="tag_single">
    <?=$tag_awal; ?>
</p>

<?php
require_once "view/footer.php";
?>