Hi there,
This is because of the HTML markup you’ve added to your pages.
For example:
<div style="width: 1098px; height: 650px; margin: 0px;">
<div style="float: left; width: 650px; height: 550px; margin: 0px; padding: 50px; border: none;">
</div>
<div style="float: left; width: 344px; height: 650px; margin: 0px; padding: 0px; border: none;">
</div>
</div>
The width and height attributes in there aren’t responsive.
If you’re wanting to create responsive columns, I suggest using this plugin: https://wordpress.org/plugins/lightweight-grid-columns/