スマホのときだけサイドバーを上部に持っていきたい

<?php
if ($this->BcBaser->isHome()) {
//$this->BcBaser->mainImage(array('all' => true, 'num' => 3, 'width' => 770));
$imageCount = 3;
$options = array_merge(array('num' => $imageCount, 'all' => true, 'id' => 'MainImage', 'width' => 770), array());
echo "<ul id=\"MainImage\">";
for ($i = 1; $i <= $imageCount; $i++) {
$options['num'] = $i;
echo "<li style='width:770px'>";
echo $this->BcBaser->_getThemeImage('main_image', $options);
echo "</li>";
}
echo "</ul>";

echo "<nav>";
$this->BcBaser->blogPosts("data", $top_count, array("tag" => "TOP"));
echo "</nav>";

echo "<nav>";
$this->BcBaser->element('sidebox');
echo "</nav>";

<nav>
<?php $this->BcBaser->element('sidebox') ?>
</nav>