Prova questo codice:
Codice:
<head>
<style type="text/css">
/* Google AdSense LeaderBoard 728x90 specific settings */
.adsense {
position: relative;
width: 728px;
margin: auto;
}
.adsense_container {
/* configurazioni specifiche container tipo bordo, sfondo, ecc */
background-color: rgb(240,240,240);
min-height: 90px;
padding: 10px;
}
</style>
<!-- Privacy/Cookie policy -->
<style type="text/css">
/*IUBENDA STYLE*/
</style>
<script type="text/javascript">
//IUBENDA POLICY
</script>
</head>
<body>
<div class="adsense_container">
<div class="adsense">
<script type="text/javascript">
/* <![CDATA[ */
document.write('<s'+'cript type="text/javascript" src="http://ad.altervista.org/js.ad/size=728X90/?ref='+encodeURIComponent(location.hostname+location.pathname)+'&r='+new Date().getTime()+'"></s'+'cript>');
/* ]]> */
</script>
</div>
</div>
...
è importante la proprietà margin: auto; del container interno