icingaweb2/application/layouts/scripts/parts/navigation.phtml

<div id="menu-header"><img src="<?= $this->href('img/logo_icinga-inv.png') ?>" style="height: 2em; width:6em; float: left; margin-left: 1.5em; margin-right: 9em; margin-top: 0.5em;" alt="" /></div>
<div id="menu">
<input type="text" style="width: 9em; margin: 0.5em;background-color: #999; background-image: url('<?= $this->href('img/icons/search.png') ?>'); background-repeat: no-repeat; background-position: 0.8em center; padding: 0.3em; padding-left: 2.5em; border: none; color: #F5F5F5; text-shadow: -1px 1px 0 #555555;" placeholder="Search..." />
<?php
// determine current key
$url = Icinga\Web\Url::fromRequest()->getRelativeUrl();
$menu = Icinga\Web\Menu::fromConfig();

if ($this->auth()->isAuthenticated()) {
    echo $this->partial(
       'parts/menu.phtml',
        array(
            'items' => $menu->getChildren(),
            'url'   => $url
        )
    );
}
?>
</div>