Date Dependent Stylesheets

<?php
$dateShort = date('md');

if ($dateShort >= "0101" && $dateShort <= "0131") {
    $cssTheme = "newyear";
} elseif ($dateShort >= "1020" && $dateShort <= "1031") {
    $cssTheme = "halloween";
} elseif ($dateShort >= "1212" && $dateShort <= "1231") {
    $cssTheme = "christmas";
} else {
    $cssTheme = "default";
}
?>

<link type="text/css" rel="stylesheet" href="css/<?= $cssTheme ?>.css">