Victor12 I have managed to fix it. When adding the code to your add section just add a <style></style> and do as google explains here -> https://support.google.com/adsense/answer/6307124?hl=en
My code (codes replaced by "XXXX" and added the tag "under_tag"):
<style>
@media(max-width: 800px) { .under_tags { width: 468px; height: 60px; margin: auto; } .item-flagrow-ad{margin: 0px -15px 0px -15px;}}
</style>
<script async src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<!-- under_tags -->
<ins class="adsbygoogle under_tags"
style="display:block"
data-ad-client="ca-pub-XXXXXXX11XXX9"
data-ad-slot="8XXXXX1"
data-ad-format="auto"
data-full-width-responsive="true"></ins>
<script>
(adsbygoogle = window.adsbygoogle || []).push({});
</script>
No need to worry about getting kicked by AdSense since the code is copied from their help center.
You can even hide it for certain sizes if you want by doing display: none;
In the mobile there seem to be a padding on the left that I'm trying to fix yet but besides that it works -fixed
